/* CodeCraft — "Notebook" theme, Python palette (approved 2026-10-07; see design/options.html). */

/* ================= TOKENS ================= */
:root {
  --a1: #3B82F6; --a2: #FFD43B; --a3: #8B5CF6; --hl: #FFE45C;
  --ink-l: #1D4ED8; --ink-d: #8CBBFF;
  --font-d: 'Bricolage Grotesque', system-ui, sans-serif;
  --font-b: 'Atkinson Hyperlegible', system-ui, sans-serif;
  --font-m: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, monospace;
  --font-h: 'Caveat', 'Comic Sans MS', cursive;
  --radius: 14px; --radius-sm: 9px; --pill: 12px;
  --top-h: 64px;
}
:root, :root[data-mode=light] {
  color-scheme: light;
  --bg: #F6F3E8; --grid: rgba(60,110,190,.11);
  --text: #22252D; --muted: #5C616E; --faint: #8A8E99;
  --surface: #FFFEFA; --surface-2: #F9F6EC; --border: #E3DDCB; --border-2: #CFC6AC;
  --shadow: 0 1px 0 #E3DDCB, 0 12px 24px -18px rgba(80,60,20,.35);
  --top-bg: rgba(246,243,232,.92);
  --code-bg: #FCFBF5; --code-text: #22252D; --code-com: #8F918A; --code-ln: #BDB7A3; --con-bg: #F2EFE3;
  --margin: rgba(225,80,80,.45); --hlc: var(--hl);
  --ink: var(--ink-l);
  --ok: #15803D; --bad: #BE123C; --ok-bg: rgba(21,128,61,.09); --bad-bg: rgba(190,18,60,.08);
  --tk-kw: #1D4ED8; --tk-str: #9A6700; --tk-num: #7C3AED; --tk-fn: #0F766E;
}
:root[data-mode=dark] {
  color-scheme: dark;
  --bg: #15171C; --grid: rgba(255,255,255,.045);
  --text: #E9E7E0; --muted: #A6A69E; --faint: #7C7E78;
  --surface: #1D2027; --surface-2: #23272F; --border: #2E333D; --border-2: #3E4450;
  --shadow: 0 12px 24px -18px rgba(0,0,0,.7);
  --top-bg: rgba(21,23,28,.92);
  --code-bg: #181B21; --code-text: #E9E7E0; --code-com: #7A7F78; --code-ln: #4A505A; --con-bg: #111317;
  --margin: rgba(255,110,110,.32); --hlc: color-mix(in srgb, var(--hl) 34%, transparent);
  --ink: var(--ink-d);
  --ok: #34D399; --bad: #FB7185; --ok-bg: rgba(52,211,153,.13); --bad-bg: rgba(251,113,133,.13);
  --tk-kw: #7AB4FF; --tk-str: #FFD866; --tk-num: #C6A8FF; --tk-fn: #5EEAD4;
}

/* ================= BASE ================= */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; min-height: 100vh; background: var(--bg); color: var(--text);
  font-family: var(--font-b); font-size: 16px; line-height: 1.62; -webkit-font-smoothing: antialiased;
  overflow-x: hidden; transition: background-color .3s, color .3s;
  /* Code must show >= and != exactly as typed — no font ligatures anywhere. */
  font-variant-ligatures: no-contextual; font-feature-settings: 'calt' 0, 'liga' 0;
}
button { font: inherit; color: inherit; cursor: pointer; }
a { color: inherit; }
h1, h2, h3, h4 { margin: 0; }
:focus-visible { outline: 2.5px solid var(--a1); outline-offset: 2px; border-radius: 4px; }
.ic { width: 16px; height: 16px; flex: none; stroke: currentColor; fill: none; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
kbd { font-family: var(--font-m); font-size: .82em; padding: 1px 6px; border: 1px solid var(--border-2); border-bottom-width: 2px; border-radius: 5px; background: var(--surface); }
.muted { color: var(--faint); }
.skip { position: absolute; left: 12px; top: -60px; z-index: 100; padding: 8px 14px; background: var(--ink); color: var(--bg); border-radius: 8px; text-decoration: none; font-weight: 700; }
.skip:focus { top: 12px; }
.bg { position: fixed; inset: 0; z-index: 0; pointer-events: none; background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px); background-size: 24px 24px; }

/* ================= SHELL + LAYOUTS ================= */
.app { position: relative; z-index: 1; display: grid; min-height: 100vh; }
.topbar { grid-area: top; }
.sidebar { grid-area: side; }
.main { grid-area: main; min-width: 0; outline: none; }
.dock { grid-area: dock; display: none; min-width: 0; min-height: 0; flex-direction: column; }

/* Home: sidebar layout */
[data-screen=home] .app, [data-screen=practice] .app { grid-template-columns: 300px minmax(0, 1fr); grid-template-rows: auto 1fr; grid-template-areas: "top top" "side main"; }
[data-screen=home] .main, [data-screen=practice] .main { padding: 30px clamp(16px, 4vw, 48px) 64px; }
[data-screen=home] .main > *, [data-screen=practice] .main > * { max-width: 1040px; margin-left: auto; margin-right: auto; }
/* Lesson: split IDE layout */
[data-screen=lesson] .app { grid-template-columns: minmax(0, 1fr) minmax(0, 1.04fr); grid-template-rows: auto minmax(0, 1fr); grid-template-areas: "top top" "main dock"; height: 100vh; height: 100dvh; }
[data-screen=lesson] .sidebar { display: none; }
[data-screen=lesson] .main { overflow: auto; padding: 26px 30px 48px; scroll-behavior: smooth; }
[data-screen=lesson] .dock { display: flex; padding: 18px 18px 18px 0; }

/* ================= TOP BAR ================= */
.topbar { position: sticky; top: 0; z-index: 30; display: flex; align-items: center; gap: 14px; min-height: var(--top-h); padding: 10px clamp(14px, 2.4vw, 26px); background: var(--top-bg); backdrop-filter: blur(14px); -webkit-backdrop-filter: blur(14px); border-bottom: 1px solid var(--border); }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--text); flex: none; }
.logo { width: 34px; height: 34px; border-radius: 10px; display: grid; place-items: center; background: var(--ink); color: var(--bg); transform: rotate(-4deg); box-shadow: 0 3px 0 color-mix(in srgb, var(--ink) 60%, #000); }
.logo .ic { width: 20px; height: 20px; stroke-width: 2.4; }
.brand-name { display: block; font-family: var(--font-d); font-size: 21px; font-weight: 800; letter-spacing: -.01em; line-height: 1; }
.brand-sub { display: block; font-family: var(--font-h); font-size: 15px; color: var(--ink); line-height: 1.2; }
.icon-btn.menu-btn { display: none; }
[data-screen=lesson] .icon-btn.menu-btn { display: grid; }
.crumbs { display: none; align-items: center; gap: 8px; min-width: 0; font-size: 14px; color: var(--muted); }
[data-screen=lesson] .crumbs { display: flex; }
.crumb-mod { display: flex; align-items: center; gap: 6px; padding: 6px 11px; border: 1px solid var(--border); border-radius: var(--pill); background: var(--surface); white-space: nowrap; color: var(--text); font-weight: 600; font-size: 13.5px; }
.crumb-mod:hover { border-color: var(--border-2); }
.crumb-mod .ic, .crumbs > .ic { width: 14px; height: 14px; }
.crumb-les { color: var(--text); font-weight: 700; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.top-right { margin-left: auto; display: flex; align-items: center; gap: 8px; }
.chip-stat { display: flex; align-items: center; gap: 6px; padding: 6px 11px; border-radius: var(--pill); border: 1px solid var(--border); background: var(--surface); font-size: 13px; font-weight: 700; white-space: nowrap; }
.chip-stat .ic { color: #E8590C; width: 15px; height: 15px; }
[data-mode=dark] .chip-stat .ic { color: var(--a2); }
.chip-stat.xp { gap: 8px; }
.xpbar { width: 64px; height: 6px; border-radius: 9px; background: var(--surface-2); overflow: hidden; box-shadow: inset 0 0 0 1px var(--border); }
.xpbar i { display: block; height: 100%; background: linear-gradient(90deg, var(--a1), var(--a3)); border-radius: inherit; }
.icon-btn { width: 38px; height: 38px; display: grid; place-items: center; border-radius: var(--pill); border: 1px solid var(--border); background: var(--surface); flex: none; }
.icon-btn:hover { border-color: var(--border-2); }
[data-mode=dark] .i-sun-w, [data-mode=light] .i-moon-w { display: none; }
:root:not([data-mode]) .i-sun-w { display: none; }

/* ================= SIDEBAR + DRAWER (course tree) ================= */
.sidebar { position: sticky; top: var(--top-h); align-self: start; height: calc(100vh - var(--top-h)); overflow: auto; padding: 20px 14px 28px 18px; border-right: 1px solid var(--border); background: color-mix(in srgb, var(--surface) 70%, transparent); }
.side-prog { display: flex; align-items: center; gap: 12px; padding: 14px; margin-bottom: 16px; }
.side-prog b { display: block; font-size: 14.5px; }
.side-prog span { font-size: 13px; color: var(--muted); }
.mini-ring { width: 46px; height: 46px; flex: none; position: relative; }
.mini-ring svg { width: 100%; height: 100%; transform: rotate(-90deg); }
.mini-ring em { position: absolute; inset: 0; display: grid; place-items: center; font-style: normal; font-size: 12px; font-weight: 700; font-family: var(--font-m); }
.side-label { font-size: 11px; letter-spacing: .12em; text-transform: uppercase; color: var(--faint); font-weight: 700; margin: 6px 10px 8px; font-family: var(--font-m); }
.modnav, .les { list-style: none; margin: 0; padding: 0; }
.mod-h { display: flex; align-items: center; gap: 10px; width: 100%; padding: 7px 10px; border-radius: var(--radius-sm); border: 0; background: none; text-align: left; font-size: 14.5px; color: var(--text); line-height: 1.3; }
.mod-h:hover { background: var(--surface-2); }
.mod-n { width: 26px; height: 26px; flex: none; display: grid; place-items: center; border-radius: 8px; font-size: 12px; font-weight: 700; font-family: var(--font-m); background: var(--surface-2); border: 1px solid var(--border); color: var(--muted); }
.mod.done .mod-n { background: var(--ok-bg); color: var(--ok); border-color: transparent; }
.mod.cur .mod-n { background: var(--ink); color: var(--bg); border-color: transparent; }
.mod-t { flex: 1; min-width: 0; }
.mod-t small { display: block; color: var(--faint); font-size: 11px; font-family: var(--font-m); }
.mod-c { font-size: 11.5px; color: var(--faint); font-family: var(--font-m); }
.mod-h .chev { width: 14px; height: 14px; color: var(--faint); transition: transform .2s; }
.mod-h[aria-expanded=true] .chev { transform: rotate(90deg); }
.les { margin: 2px 0 8px 22px; padding-left: 12px; border-left: 1px solid var(--border); }
.les[hidden] { display: none; }
.les a { display: flex; align-items: center; gap: 8px; padding: 6px 10px; border-radius: 8px; font-size: 14px; color: var(--muted); text-decoration: none; line-height: 1.35; }
.les a:hover { color: var(--text); background: var(--surface-2); }
.les a .ic { width: 14px; height: 14px; color: var(--ok); }
.les .dot { width: 14px; height: 14px; border-radius: 50%; border: 1.5px solid var(--border-2); flex: none; }
.les a.started .dot { border-color: var(--a1); background: linear-gradient(90deg, var(--a1) 50%, transparent 50%); }
.les a.active { background: color-mix(in srgb, var(--a1) 13%, transparent); color: var(--text); font-weight: 700; box-shadow: inset 2px 0 0 var(--a1); }
.les a.active .dot { border-color: var(--a1); background: radial-gradient(circle, var(--a1) 40%, transparent 45%); }
.side-note { margin-top: 18px; padding: 14px; display: flex; flex-direction: column; gap: 8px; font-size: 13px; color: var(--muted); }
.side-note b { font-size: 14px; color: var(--text); }
.drawer { position: fixed; inset: 0; z-index: 60; }
.drawer[hidden] { display: none; }
.drawer-backdrop { position: absolute; inset: 0; background: rgba(20,18,10,.35); animation: fade .2s; }
.drawer-panel { position: absolute; left: 0; top: 0; bottom: 0; width: min(340px, 88vw); background: var(--bg); border-right: 1px solid var(--border); box-shadow: 20px 0 40px -20px rgba(0,0,0,.35); display: flex; flex-direction: column; animation: slide .22s ease-out; }
.drawer-top { display: flex; align-items: center; justify-content: space-between; padding: 12px 14px; border-bottom: 1px solid var(--border); }
.drawer-body { overflow: auto; padding: 14px 12px 28px 14px; }
@keyframes fade { from { opacity: 0; } }
@keyframes slide { from { transform: translateX(-100%); } }

/* ================= COMPONENTS ================= */
.card { position: relative; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); }
.card.tape::before { content: ""; position: absolute; top: -11px; left: 50%; width: 92px; height: 24px; transform: translateX(-50%) rotate(-3deg); background: color-mix(in srgb, var(--hl) 75%, transparent); opacity: .85; border-radius: 2px; box-shadow: 0 1px 2px rgba(0,0,0,.08); z-index: 2; }
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 8px; padding: 9px 16px; border-radius: 10px; border: 1px solid var(--border-2); background: var(--surface-2); color: var(--text); font-weight: 700; font-size: 14px; line-height: 1.2; white-space: nowrap; text-decoration: none; box-shadow: 0 2px 0 var(--border-2); transition: transform .12s, box-shadow .12s; }
.btn:hover { transform: translateY(-1px); }
.btn:active { transform: translateY(1px); box-shadow: 0 1px 0 var(--border-2); }
.btn.sm { padding: 6px 12px; font-size: 13px; }
.btn .ic { width: 15px; height: 15px; }
.btn.primary { background: var(--ink); color: var(--bg); border-color: transparent; box-shadow: 0 3px 0 color-mix(in srgb, var(--ink) 60%, #000); }
.btn.done { background: var(--ok-bg); color: var(--ok); border-color: color-mix(in srgb, var(--ok) 40%, transparent); box-shadow: none; }
.tag { display: inline-flex; align-items: center; gap: 6px; font-size: 12.5px; font-weight: 700; padding: 4px 11px; border-radius: var(--pill); border: 1px solid var(--border); background: var(--surface); color: var(--muted); white-space: nowrap; }
.tag .ic { width: 13px; height: 13px; }
.tag-ref { color: var(--ink); border-color: color-mix(in srgb, var(--a1) 45%, transparent); background: color-mix(in srgb, var(--a1) 12%, transparent); font-family: var(--font-m); }
.tag-sl { color: #111; background: var(--a2); border-color: transparent; font-weight: 800; }
code { font-family: var(--font-m); font-size: .88em; }
.prose code, .friendly code, .files-empty code, .soon code { padding: .08em .38em; border-radius: 6px; background: var(--surface-2); border: 1px solid var(--border); color: var(--ink); }
.term { font-weight: 700; color: var(--text); background: linear-gradient(100deg, transparent .15em, var(--hlc) .15em, var(--hlc) calc(100% - .2em), transparent calc(100% - .2em)) 0 70% / 100% 70% no-repeat; padding: 0 .3em; }
.anno { display: flex; align-items: center; gap: 8px; font-family: var(--font-h); font-size: 23px; line-height: 1.1; color: var(--ink); transform: rotate(-2deg); transform-origin: left; margin: 18px 0 0 6px; }
.anno::after { content: ""; width: 34px; height: 18px; flex: none; background: no-repeat center / contain url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 34 18' fill='none' stroke='%23888' stroke-width='2' stroke-linecap='round'><path d='M2 14C10 4 20 3 31 7M31 7l-6-5M31 7l-6 4'/></svg>"); }

/* ================= LESSON ================= */
.tags { display: flex; flex-wrap: wrap; gap: 8px; }
.lesson-title { font-family: var(--font-d); font-weight: 800; font-size: clamp(32px, 4.4vw, 50px); line-height: 1.06; letter-spacing: -.03em; margin: 16px 0 12px; }
.lesson-title em { font-style: normal; background: linear-gradient(transparent 56%, var(--hlc) 56%, var(--hlc) 92%, transparent 92%); padding: 0 .06em; -webkit-box-decoration-break: clone; box-decoration-break: clone; }
.lede { font-size: 1.1em; color: var(--muted); max-width: 60ch; margin: 0; }
.lpath { list-style: none; margin: 16px 0 0; padding: 0; display: flex; flex-wrap: wrap; gap: 6px 4px; align-items: center; }
.lpath li { display: flex; align-items: center; gap: 4px; }
.lpath li + li::before { content: ""; width: 16px; height: 1.5px; background: var(--border-2); margin-right: 4px; }
.lpath a { display: flex; align-items: center; gap: 7px; font-size: 12.5px; color: var(--faint); font-weight: 700; text-decoration: none; padding: 2px 4px; border-radius: 6px; }
.lpath a:hover { color: var(--text); }
.lpath i { width: 10px; height: 10px; border-radius: 50%; border: 1.5px solid var(--border-2); flex: none; }
.lpath .done a { color: var(--muted); } .lpath .done i { background: var(--ok); border-color: var(--ok); }
.lpath .cur a { color: var(--text); } .lpath .cur i { background: var(--a1); border-color: var(--a1); box-shadow: 0 0 0 4px color-mix(in srgb, var(--a1) 25%, transparent); }
.steps { display: flex; gap: 4px; padding: 5px; margin: 24px 0 6px; border: 1px solid var(--border); border-radius: var(--pill); background: var(--surface); box-shadow: var(--shadow); position: sticky; top: -12px; z-index: 10; width: max-content; max-width: 100%; overflow-x: auto; scrollbar-width: none; }
.st { display: flex; align-items: center; gap: 8px; padding: 6px 14px 6px 7px; border: 0; border-radius: 9px; background: none; color: var(--muted); font-weight: 700; font-size: 14px; white-space: nowrap; }
.st:hover { color: var(--text); }
.st-n { width: 23px; height: 23px; border-radius: 50%; display: grid; place-items: center; font-size: 11.5px; font-family: var(--font-m); background: var(--surface-2); border: 1px solid var(--border); }
.st-n .ic { width: 13px; height: 13px; stroke-width: 3; }
.st.on { background: var(--surface-2); color: var(--text); box-shadow: inset 0 0 0 1px var(--border-2); }
.st.on .st-n { background: var(--ink); color: var(--bg); border-color: transparent; }
.st.done .st-n { background: var(--ok-bg); color: var(--ok); border-color: transparent; }
.step { scroll-margin-top: 64px; }
.sec-head { display: flex; align-items: center; gap: 12px; margin: 38px 0 14px; }
.step:first-of-type .sec-head { margin-top: 24px; }
.sec-k { font-family: var(--font-h); font-size: 22px; font-weight: 700; width: 36px; height: 36px; flex: none; display: grid; place-items: center; border: 2px solid var(--ink); color: var(--ink); border-radius: 50%; transform: rotate(-6deg); line-height: 1; }
.sec-head h2 { font-family: var(--font-d); font-size: 28px; font-weight: 800; letter-spacing: -.02em; line-height: 1.1; }
.sec-head .btn { margin-left: auto; }
.prose { padding: 24px 26px 24px 58px; background-image: linear-gradient(90deg, transparent 34px, var(--margin) 34px, var(--margin) 35.5px, transparent 35.5px); }
.prose p { margin: 0 0 14px; max-width: 68ch; }
.prose p:last-child { margin-bottom: 0; }
.prose h3 { font-family: var(--font-d); font-size: 18px; font-weight: 800; margin: 0 0 10px; }
.must { list-style: none; margin: 0; padding: 0; display: grid; gap: 8px; }
.must li { display: flex; gap: 10px; align-items: flex-start; line-height: 1.45; }
.must li::before { content: ""; width: 16px; height: 16px; margin-top: 3px; flex: none; border: 1.5px solid var(--border-2); border-radius: 4px; background: var(--surface); }
.soon { padding: 22px 24px; }
.soon-k { display: inline-flex; align-items: center; gap: 6px; font-size: 11.5px; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: #3A2E00; background: var(--a2); padding: 3px 10px; border-radius: 7px; font-family: var(--font-m); margin: 0 0 12px; }
.soon h3 { font-family: var(--font-d); font-size: 20px; font-weight: 800; letter-spacing: -.01em; margin-bottom: 6px; }
.soon p { margin: 0 0 10px; color: var(--muted); max-width: 64ch; }
.soon ul { margin: 0; padding-left: 20px; color: var(--muted); }
.soon li { margin: 3px 0; }
.lesson-nav { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 34px; }
.lesson-nav a { display: flex; flex-direction: column; gap: 2px; padding: 14px 18px; text-decoration: none; }
.lesson-nav a:hover { border-color: var(--border-2); }
.lesson-nav span { font-size: 12.5px; color: var(--faint); font-family: var(--font-m); display: flex; align-items: center; gap: 6px; }
.lesson-nav b { font-size: 16px; }
.lesson-nav .next { text-align: right; align-items: flex-end; grid-column: 2; }
.missing { padding: 30px; text-align: center; }

/* ================= PLAYGROUND ================= */
.playground { display: flex; flex-direction: column; overflow: hidden; }
.dock .playground { flex: 1; min-height: 0; }
.pg-head { display: flex; align-items: center; gap: 10px; padding: 8px 10px 8px 12px; border-bottom: 1px solid var(--border); background: var(--surface-2); flex-wrap: wrap; }
.pg-tabs { display: flex; gap: 4px; }
.pg-tab { display: flex; align-items: center; gap: 7px; padding: 6px 11px; border: 1px solid transparent; border-radius: var(--radius-sm); background: none; font-size: 13px; font-weight: 700; color: var(--muted); font-family: var(--font-m); }
.pg-tab .ic { width: 14px; height: 14px; }
.pg-tab.on { color: var(--text); background: var(--code-bg); border-color: var(--border); }
.pg-tab .count { font-size: 10.5px; padding: 0 6px; border-radius: 9px; background: var(--surface); border: 1px solid var(--border); }
.pg-actions { margin-left: auto; display: flex; gap: 6px; }
.is-running [data-act=run] { background: var(--bad); color: #fff; box-shadow: 0 3px 0 color-mix(in srgb, var(--bad) 60%, #000); }
.pg-views { position: relative; background: var(--code-bg); min-height: 0; display: flex; flex-direction: column; }
.dock .pg-views { flex: 1; }
.pg-editor { flex: 1; min-height: 0; }
.pg-editor[hidden], .pg-files[hidden] { display: none; }
.pg-editor .CodeMirror { height: 100%; min-height: 220px; }
.playground:not(.dock .playground) .pg-editor .CodeMirror { height: 340px; }
.pg-textarea { display: block; width: 100%; height: 100%; min-height: 300px; resize: none; border: 0; padding: 14px 16px; background: var(--code-bg); color: var(--code-text); font: 13.5px/1.7 var(--font-m); tab-size: 4; outline: none; }
.pg-files { flex: 1; overflow: auto; padding: 14px 16px; font-size: 13.5px; }
.files-top { display: flex; align-items: center; justify-content: space-between; gap: 10px; color: var(--faint); font-size: 12.5px; margin-bottom: 10px; flex-wrap: wrap; }
.file-list { list-style: none; margin: 0 0 10px; padding: 0; display: grid; gap: 6px; }
.file { display: flex; align-items: center; gap: 10px; width: 100%; padding: 8px 10px; border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--surface); font-family: var(--font-m); font-size: 13px; text-align: left; }
.file.on { border-color: var(--a1); box-shadow: 0 0 0 3px color-mix(in srgb, var(--a1) 15%, transparent); }
.file small { margin-left: auto; color: var(--faint); }
.file-badge { font-style: normal; font-size: 10.5px; font-weight: 700; text-transform: uppercase; letter-spacing: .05em; padding: 1px 7px; border-radius: 6px; background: var(--a2); color: #3A2E00; }
.file-pre { margin: 0; padding: 12px 14px; border-radius: var(--radius-sm); background: var(--con-bg); border: 1px solid var(--border); font: 13px/1.65 var(--font-m); white-space: pre; overflow: auto; color: var(--code-text); min-height: 60px; }
.files-empty { padding: 18px; border: 1.5px dashed var(--border-2); border-radius: var(--radius-sm); color: var(--muted); text-align: center; }
.pg-console { border-top: 1px solid var(--border); background: var(--con-bg); color: var(--code-text); display: flex; flex-direction: column; min-height: 0; }
.dock .pg-console { flex: 0 0 38%; }
.playground:not(.dock .playground) .pg-console { height: 220px; }
.con-head { display: flex; align-items: center; gap: 10px; padding: 6px 10px 6px 14px; font-size: 11px; color: var(--faint); border-bottom: 1px solid var(--border); font-family: var(--font-m); text-transform: uppercase; letter-spacing: .1em; font-weight: 700; }
.con-clear { border: 0; background: none; color: var(--faint); font-size: 11px; text-transform: uppercase; letter-spacing: .08em; font-family: var(--font-m); padding: 2px 6px; border-radius: 5px; }
.con-clear:hover { color: var(--text); background: var(--surface-2); }
.status { margin-left: auto; display: flex; align-items: center; gap: 6px; text-transform: none; letter-spacing: 0; font-size: 12px; font-weight: 500; }
.status i { width: 7px; height: 7px; border-radius: 50%; background: var(--border-2); }
.status.ok i { background: var(--ok); }
.status.run i, .status.wait i { background: #E8A100; animation: blink .8s steps(1) infinite; }
.status.err i { background: var(--bad); }
@keyframes blink { 50% { opacity: 0; } }
.con-body { flex: 1; overflow: auto; padding: 12px 16px 16px; font: 13.5px/1.6 var(--font-m); }
.con-out { white-space: pre-wrap; word-break: break-word; }
.con-echo { color: var(--ink); font-weight: 700; }
.con-input { background: transparent; border: 0; border-bottom: 2px dashed var(--a1); color: var(--ink); font: inherit; font-weight: 700; width: 14ch; max-width: 100%; outline: none; padding: 0 2px; }
.con-input:focus { border-bottom-style: solid; }
.con-hint, .con-note { color: var(--faint); font-family: var(--font-b); font-size: 13.5px; }
.con-hint kbd { font-size: 11px; }
.con-note { margin-top: 6px; font-style: italic; }
.con-err { color: var(--bad); margin-top: 4px; white-space: pre-wrap; }
.con-line-link { border: 0; background: none; padding: 0; color: inherit; font: inherit; text-decoration: underline; text-underline-offset: 3px; }
.friendly { margin-top: 10px; border: 1px solid color-mix(in srgb, var(--bad) 35%, transparent); background: var(--bad-bg); border-radius: var(--radius-sm); padding: 10px 12px; font: 14px/1.55 var(--font-b); color: var(--text); }
.friendly b { color: var(--bad); }
.friendly-link { display: inline-block; margin-top: 4px; color: var(--ink); font-weight: 700; text-decoration: none; }
.friendly-link:hover { text-decoration: underline; }
/* CodeMirror → notebook tokens */
.CodeMirror { font-family: var(--font-m); font-size: 13.5px; line-height: 1.7; background: var(--code-bg); color: var(--code-text); }
.CodeMirror-gutters { background: var(--code-bg); border-right: 1px solid var(--border); }
.CodeMirror-linenumber { color: var(--code-ln); padding: 0 10px 0 6px; }
.CodeMirror-cursor { border-left: 2px solid var(--ink); }
.CodeMirror-selected, .CodeMirror-focused .CodeMirror-selected { background: color-mix(in srgb, var(--a1) 20%, transparent); }
.CodeMirror-line::selection, .CodeMirror-line > span::selection, .CodeMirror-line > span > span::selection { background: color-mix(in srgb, var(--a1) 25%, transparent); }
.cm-s-default .cm-keyword { color: var(--tk-kw); font-weight: 700; }
.cm-s-default .cm-string { color: var(--tk-str); }
.cm-s-default .cm-number { color: var(--tk-num); }
.cm-s-default .cm-builtin, .cm-s-default .cm-def { color: var(--tk-fn); }
.cm-s-default .cm-def { font-weight: 700; }
.cm-s-default .cm-comment { color: var(--code-com); font-style: italic; }
.cm-s-default .cm-variable, .cm-s-default .cm-variable-2, .cm-s-default .cm-property { color: var(--code-text); }
.cm-s-default .cm-operator { color: var(--muted); }
.cm-s-default .cm-meta { color: var(--tk-num); }
.cm-s-default .cm-error { color: var(--bad); }
.CodeMirror-matchingbracket { color: var(--ok) !important; background: var(--ok-bg); }
.cm-errline { background: var(--bad-bg); box-shadow: inset 3px 0 0 var(--bad); }

/* ================= HOME ================= */
.home-hero { display: grid; grid-template-columns: minmax(0, 1fr) auto; gap: 30px; align-items: center; padding: 32px 34px; }
.eyebrow { font-size: 11.5px; letter-spacing: .14em; text-transform: uppercase; color: var(--ink); font-weight: 700; font-family: var(--font-m); margin: 0; }
.home-title { font-family: var(--font-d); font-size: clamp(32px, 4.4vw, 52px); line-height: 1.05; letter-spacing: -.03em; margin: 12px 0; font-weight: 800; }
.home-title em { font-style: normal; background: linear-gradient(transparent 58%, var(--hlc) 58%, var(--hlc) 92%, transparent 92%); -webkit-box-decoration-break: clone; box-decoration-break: clone; }
.home-hero .sub { margin: 0 0 20px; color: var(--muted); max-width: 54ch; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 10px; }
.ring { width: 164px; height: 164px; position: relative; flex: none; }
.ring svg { width: 100%; height: 100%; transform: rotate(-90deg); }
.ring .track { stroke: var(--border-2); }
.ring .val { transition: stroke-dashoffset 1.2s cubic-bezier(.2,.8,.2,1); }
.ring-c { position: absolute; inset: 0; display: grid; place-content: center; text-align: center; }
.ring-c b { font-family: var(--font-d); font-size: 40px; line-height: 1; font-weight: 800; }
.ring-c span { font-size: 12.5px; color: var(--muted); margin-top: 4px; }
.stats { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 14px; margin: 16px auto; }
.stat { padding: 16px 18px; display: flex; flex-direction: column; gap: 2px; }
.stat .ic { width: 20px; height: 20px; color: var(--ink); margin-bottom: 8px; }
.stat-v { font-family: var(--font-d); font-size: 30px; font-weight: 800; line-height: 1.1; letter-spacing: -.02em; }
.stat-v small { font-size: .5em; color: var(--faint); font-weight: 700; }
.stat-l { color: var(--muted); font-size: 13.5px; }
.home-grid { display: grid; grid-template-columns: minmax(0, 1fr) 300px; gap: 16px; align-items: start; }
.h2 { font-family: var(--font-d); font-size: 24px; font-weight: 800; letter-spacing: -.02em; margin: 10px 0 14px; display: flex; align-items: baseline; gap: 10px; }
.h2 span { font-family: var(--font-m); font-size: 12px; color: var(--faint); font-weight: 500; letter-spacing: 0; margin-left: auto; }
.mods { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(210px, 1fr)); gap: 12px; }
.mcard { display: flex; flex-direction: column; gap: 8px; min-height: 150px; padding: 16px; text-decoration: none; transition: transform .15s, border-color .15s; }
.mcard:hover { transform: translateY(-2px) rotate(-.3deg); border-color: var(--border-2); }
.m-top { display: flex; align-items: center; gap: 8px; }
.m-node { width: 30px; height: 30px; flex: none; border-radius: 10px; display: grid; place-items: center; font-family: var(--font-m); font-weight: 700; font-size: 13px; background: var(--surface-2); border: 1px solid var(--border); color: var(--muted); }
.mcard.done .m-node { background: var(--ok-bg); color: var(--ok); border-color: transparent; }
.mcard.cur .m-node { background: var(--ink); color: var(--bg); border-color: transparent; }
.m-code { font-family: var(--font-m); font-size: 12px; color: var(--ink); font-weight: 700; }
.m-state { margin-left: auto; font-size: 11px; font-weight: 700; letter-spacing: .04em; text-transform: uppercase; color: var(--faint); }
.mcard.done .m-state { color: var(--ok); } .mcard.cur .m-state { color: var(--ink); }
.m-title { font-weight: 700; font-size: 16px; line-height: 1.3; flex: 1; }
.m-bar { height: 6px; border-radius: 9px; background: var(--surface-2); overflow: hidden; box-shadow: inset 0 0 0 1px var(--border); }
.m-bar i { display: block; height: 100%; border-radius: inherit; background: linear-gradient(90deg, var(--a1), var(--a3)); }
.mcard.done .m-bar i { background: var(--ok); }
.m-meta { font-size: 12px; color: var(--faint); font-family: var(--font-m); }
.side-col { display: flex; flex-direction: column; gap: 14px; }
.mini { padding: 18px; }
.mini h3 { font-size: 15.5px; font-weight: 700; margin-bottom: 10px; display: flex; align-items: center; gap: 8px; }
.mini h3 .ic { color: var(--ink); }
.mini p { margin: 0 0 12px; font-size: 14px; color: var(--muted); }
.mini .anno { font-size: 21px; margin-top: 4px; }

/* ================= TOAST / FAB ================= */
.toast { position: fixed; left: 50%; bottom: 22px; transform: translate(-50%, 20px); z-index: 80; padding: 10px 16px; border-radius: 12px; background: var(--text); color: var(--bg); font-weight: 700; font-size: 14px; box-shadow: 0 14px 30px -12px rgba(0,0,0,.4); opacity: 0; pointer-events: none; transition: opacity .2s, transform .2s; }
.toast.show { opacity: 1; transform: translate(-50%, 0); }
.fab-editor { display: none; }
.cf { position: fixed; width: 8px; height: 12px; border-radius: 2px; pointer-events: none; z-index: 90; }

/* ================= RESPONSIVE ================= */
@media (max-width: 1080px) {
  .stats { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .home-grid { grid-template-columns: minmax(0, 1fr); }
  .side-col { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 900px) {
  [data-screen=lesson] .app { grid-template-columns: minmax(0, 1fr); grid-template-rows: auto auto auto; grid-template-areas: "top" "main" "dock"; height: auto; }
  [data-screen=lesson] .main { overflow: visible; padding: 22px 16px 16px; }
  [data-screen=lesson] .dock { padding: 0 16px 90px; scroll-margin-top: calc(var(--top-h) + 8px); }
  .dock .playground { height: 82vh; min-height: 520px; }
  .steps { top: calc(var(--top-h) + 8px); }
  .step { scroll-margin-top: calc(var(--top-h) + 70px); }
  [data-screen=lesson] .fab-editor { display: flex; align-items: center; gap: 8px; position: fixed; right: 16px; bottom: 16px; z-index: 40; padding: 11px 16px; border-radius: 14px; border: 0; background: var(--ink); color: var(--bg); font-weight: 700; box-shadow: 0 3px 0 color-mix(in srgb, var(--ink) 60%, #000), 0 12px 24px -10px rgba(0,0,0,.4); }
  .crumb-les, .crumbs > .ic { display: none; }
}
@media (max-width: 780px) {
  [data-screen=home] .app, [data-screen=practice] .app { grid-template-columns: minmax(0, 1fr); grid-template-areas: "top" "main"; }
  [data-screen=home] .sidebar, [data-screen=practice] .sidebar { display: none; }
  [data-screen=home] .icon-btn.menu-btn, [data-screen=practice] .icon-btn.menu-btn { display: grid; }
  .top-link span { display: none; }
  .chip-stat.xp { display: none; }
  .home-hero { grid-template-columns: minmax(0, 1fr); padding: 24px 20px; }
  .ring { width: 128px; height: 128px; }
  .ring-c b { font-size: 32px; }
  .side-col { grid-template-columns: minmax(0, 1fr); }
  .prose { padding: 20px 18px 20px 40px; background-image: linear-gradient(90deg, transparent 24px, var(--margin) 24px, var(--margin) 25.5px, transparent 25.5px); }
  .soon { padding: 20px 18px; }
  .lesson-nav { grid-template-columns: minmax(0, 1fr); }
  .lesson-nav .next { grid-column: 1; }
}
@media (max-width: 520px) {
  /* Phone header: tighter spacing so menu, logo, Practice, My questions, streak and mode all fit on one line. */
  .topbar { gap: 6px; padding: 8px 10px; }
  .top-right { gap: 6px; }
  .logo { width: 30px; height: 30px; }
  .brand { gap: 8px; min-width: 0; }
  .brand-name { font-size: 18px; }
  .icon-btn { width: 34px; height: 34px; }
  .top-link { padding: 6px 8px; }
  .chip-stat.streak { padding: 6px 8px; }
  .brand-sub { display: none; }
  [data-screen=lesson] .crumbs { display: none; }
  .streak .streak-l { display: none; }
  .st-l { display: none; }
  .st { padding: 6px 9px; }
  .stats { gap: 10px; }
  .stat { padding: 14px; }
  .pg-head { padding: 8px; }
  .pg-actions .btn:first-child span { display: none; }
}
@media (max-width: 400px) { .topbar, .top-right { gap: 4px; } .top-link { padding: 6px 7px; } }
@media (max-width: 360px) { .chip-stat.streak { display: none; } }
@media (max-width: 340px) { .brand-name { display: none; } }
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { animation: none !important; transition: none !important; scroll-behavior: auto !important; } }
.fab-editor .up { transform: rotate(90deg); }

/* ================= PRACTICE ================= */
.top-link { display: flex; align-items: center; gap: 6px; padding: 7px 12px; border-radius: var(--pill); border: 1px solid var(--border); background: var(--surface); text-decoration: none; font-weight: 700; font-size: 13.5px; white-space: nowrap; }
.top-link:hover { border-color: var(--border-2); }
.top-link .ic { color: var(--ink); width: 18px; height: 18px; }
[data-screen=practice]:not([data-sub=review]) #practiceLink, [data-sub=review] #reviewLink { background: var(--ink); color: var(--bg); border-color: transparent; }
[data-screen=practice]:not([data-sub=review]) #practiceLink .ic, [data-sub=review] #reviewLink .ic { color: var(--bg); }
.top-link + .top-link { margin-left: 0; }
.top-link { margin-left: auto; }
.top-link + .top-right { margin-left: 8px; }
.eyebrow .ic { width: 14px; height: 14px; vertical-align: -2px; margin-right: 4px; }
.ptree { display: flex; flex-direction: column; gap: 2px; }
.ptree .side-label { margin-top: 14px; }
.pt-link { display: flex; align-items: center; gap: 8px; padding: 6px 10px; border-radius: 8px; font-size: 14px; color: var(--muted); text-decoration: none; line-height: 1.35; }
.pt-link:hover { color: var(--text); background: var(--surface-2); }
.pt-link span { flex: 1; min-width: 0; }
.pt-link.active { background: color-mix(in srgb, var(--a1) 13%, transparent); color: var(--text); font-weight: 700; box-shadow: inset 2px 0 0 var(--a1); }
.pt-mix { font-weight: 700; color: var(--text); }
.pt-mix .ic { color: var(--ink); }
.pt-acc { font-style: normal; font-family: var(--font-m); font-size: 11px; font-weight: 700; padding: 1px 6px; border-radius: 6px; }
.pt-acc.good { background: var(--ok-bg); color: var(--ok); } .pt-acc.mid { background: color-mix(in srgb, var(--a2) 30%, transparent); color: var(--text); } .pt-acc.low { background: var(--bad-bg); color: var(--bad); }
.pmod { margin-top: 26px; }
.pcard { min-height: 132px; }
.pcard .m-meta { font-family: var(--font-b); font-size: 12.5px; }
.pnote { margin-top: 26px; font-size: 13.5px; color: var(--faint); max-width: 75ch; }
.weak { list-style: none; margin: 0 0 12px; padding: 0; display: grid; gap: 10px; }
.weak a { display: block; text-decoration: none; font-size: 14px; }
.weak a > div:first-child { display: flex; justify-content: space-between; gap: 8px; margin-bottom: 5px; }
.weak code { font-size: 12px; color: var(--ink); margin-right: 6px; }
.weak .m-bar i { background: linear-gradient(90deg, var(--bad), var(--a2)); }
.practice-cta { display: flex; align-items: center; gap: 20px; margin-top: 38px; padding: 22px 24px; flex-wrap: wrap; }
.practice-cta > div { flex: 1 1 320px; }
.practice-cta h3 { font-family: var(--font-d); font-size: 21px; font-weight: 800; letter-spacing: -.01em; margin: 6px 0; }
.practice-cta p { margin: 0; color: var(--muted); }
.pr-wrap { max-width: 860px; }
.pr-head .lesson-title { font-size: clamp(28px, 4vw, 42px); }
.pr-session { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 14px; }
.pr-session .chip-stat { font-weight: 600; }
.pr-next { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 16px; }
#qHost { margin-top: 20px; }

/* question card */
.q-card { padding: 22px 24px; }
.q-meta { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin-bottom: 14px; }
.q-term { font-family: var(--font-h); font-size: 22px; font-weight: 700; color: var(--ink); line-height: 1; }
.q-marks { font-family: var(--font-m); font-size: 12.5px; font-weight: 700; color: var(--muted); }
.q-kind { margin-left: auto; font-size: 12px; font-weight: 700; letter-spacing: .06em; text-transform: uppercase; color: var(--faint); font-family: var(--font-m); }
.q-prompt { font-size: 17px; line-height: 1.55; }
.q-prompt p { margin: 0 0 10px; }
.q-prompt code, .q-feedback code, .why code, .q-ban code, .q-hint code, .t-friendly code, .q-steps code, .ms-list code { font-family: var(--font-m); font-size: .86em; padding: .05em .35em; border-radius: 5px; background: var(--surface-2); border: 1px solid var(--border); color: var(--ink); }
.q-prompt blockquote { margin: 12px 0 0; padding: 12px 16px; border-left: 4px solid var(--hl); background: var(--surface-2); border-radius: 0 var(--radius-sm) var(--radius-sm) 0; font-size: 16px; }
.q-lines { display: grid; gap: 6px; margin-top: 12px; }
.q-lines div { display: flex; gap: 10px; align-items: center; }
.q-lines b { width: 26px; height: 26px; display: grid; place-items: center; border-radius: 50%; border: 2px solid var(--ink); color: var(--ink); font-family: var(--font-h); font-size: 18px; flex: none; }
.q-class { margin-top: 10px; font-size: 14px; }
.q-class summary { cursor: pointer; color: var(--ink); font-weight: 700; }
.q-code, .q-pre, .q-expected, .q-run-out { margin: 14px 0 0; padding: 12px 0; background: var(--code-bg); color: var(--code-text); border: 1px solid var(--border); border-radius: var(--radius-sm); font: 13.5px/1.7 var(--font-m); overflow-x: auto; }
.q-code { counter-reset: ln; white-space: normal; }
.q-code .l { display: block; white-space: pre; padding-right: 16px; min-height: 1.7em; }
.q-code .l::before { counter-increment: ln; content: counter(ln); display: inline-block; width: 3em; padding-right: 1.1em; text-align: right; color: var(--code-ln); user-select: none; }
.q-pre, .q-expected, .q-run-out { padding: 12px 16px; white-space: pre; }
.q-code .cm-keyword { color: var(--tk-kw); font-weight: 700; } .q-code .cm-string { color: var(--tk-str); } .q-code .cm-number { color: var(--tk-num); }
.q-code .cm-builtin, .q-code .cm-def { color: var(--tk-fn); } .q-code .cm-comment { color: var(--code-com); font-style: italic; } .q-code .cm-operator { color: var(--muted); } .q-code .cm-meta { color: var(--tk-num); }
.q-files { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 14px; }
.q-file { margin: 0; flex: 1 1 220px; border: 1px solid var(--border); border-radius: var(--radius-sm); overflow: hidden; background: var(--con-bg); }
.q-file figcaption { display: flex; align-items: center; gap: 7px; padding: 6px 12px; font: 700 12.5px var(--font-m); border-bottom: 1px solid var(--border); background: var(--surface-2); }
.q-file pre { margin: 0; padding: 10px 14px; font: 13px/1.6 var(--font-m); white-space: pre; overflow-x: auto; }
.q-visual { margin-top: 14px; overflow-x: auto; }
.q-body { margin-top: 18px; }
.q-label { display: block; font-size: 13.5px; font-weight: 700; color: var(--muted); margin-bottom: 6px; }
.q-out, .q-written { width: 100%; font: 14px/1.6 var(--font-m); padding: 10px 12px; border: 1.5px solid var(--border-2); border-radius: var(--radius-sm); background: var(--code-bg); color: var(--text); resize: vertical; }
.q-written { font-family: var(--font-b); font-size: 15px; }
.q-out:focus, .q-written:focus, .tt input:focus, .tt-extra input:focus { outline: none; border-color: var(--a1); box-shadow: 0 0 0 3px color-mix(in srgb, var(--a1) 22%, transparent); }
.q-actions { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-top: 16px; }
.q-actions:empty { display: none; }
.q-feedback { margin-top: 16px; padding: 14px 16px; border-radius: var(--radius-sm); border: 1px solid var(--border); background: var(--surface-2); }
.q-feedback.ok { border-color: color-mix(in srgb, var(--ok) 40%, transparent); background: var(--ok-bg); }
.q-feedback.bad { border-color: color-mix(in srgb, var(--bad) 35%, transparent); background: var(--bad-bg); }
.q-feedback > :last-child { margin-bottom: 0; }
.q-feedback p { margin: 0 0 10px; }
.q-verdict { display: flex; align-items: center; gap: 8px; font-family: var(--font-d); font-size: 19px; font-weight: 800; }
.ok .q-verdict { color: var(--ok); } .bad .q-verdict { color: var(--bad); }
.q-verdict .ic { width: 20px; height: 20px; stroke-width: 3; }
.q-sub { font-size: 12px; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--faint); font-family: var(--font-m); margin: 12px 0 6px !important; }
.q-steps { margin: 0 0 10px; padding-left: 20px; }
.q-steps li { margin: 4px 0; }
.q-run { margin-top: 12px; }
.q-run .q-run-out { margin-top: 8px; }
/* multiple choice */
.opts { list-style: none; margin: 0; padding: 0; display: grid; gap: 9px; }
.opt { display: flex; align-items: center; gap: 12px; width: 100%; text-align: left; padding: 12px 14px; border-radius: var(--radius-sm); border: 1.5px solid var(--border); background: var(--surface); font-size: 15.5px; line-height: 1.45; transition: border-color .15s, transform .12s; }
.opt:not(:disabled):hover { border-color: var(--border-2); transform: translateX(2px); }
.opt:disabled { cursor: default; }
.opt.mono code { font: 13.5px/1.6 var(--font-m); white-space: pre-wrap; background: none; border: 0; padding: 0; color: var(--text); }
.opt-t { flex: 1; min-width: 0; }
.opt-k { width: 28px; height: 28px; flex: none; border-radius: 8px; display: grid; place-items: center; font-size: 13px; font-weight: 800; border: 1.5px solid var(--border-2); font-family: var(--font-m); }
.opt .ic { margin-left: auto; width: 20px; height: 20px; stroke-width: 3; display: none; flex: none; }
.why { display: none; margin: 6px 4px 4px 54px; font-size: 14px; line-height: 1.5; color: var(--muted); }
.opts.show .why { display: block; }
.opts.show li.right .opt { border-color: var(--ok); background: var(--ok-bg); }
.opts.show li.right .opt-k { background: var(--ok); color: #fff; border-color: transparent; }
.opts.show li.right .i-ok { display: block; color: var(--ok); }
.opts.show li.right .why { color: var(--text); }
.opts.show li.picked:not(.right) .opt { border-color: var(--bad); background: var(--bad-bg); }
.opts.show li.picked:not(.right) .i-no { display: block; color: var(--bad); }
.opts.show li:not(.right):not(.picked) .opt { opacity: .75; }
/* trace tables */
.tt-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: var(--radius-sm); }
.tt { width: 100%; border-collapse: collapse; font: 14px var(--font-m); }
.tt th { text-align: left; font-weight: 700; font-size: 12.5px; color: var(--muted); padding: 9px 12px; background: var(--surface-2); border-bottom: 1px solid var(--border); white-space: nowrap; }
.tt td { padding: 6px 10px; border-bottom: 1px solid var(--border); vertical-align: top; }
.tt tr:last-child td { border-bottom: 0; }
.tt td + td, .tt th + th { border-left: 1px solid var(--border); }
.tt td.given { color: var(--text); padding-top: 11px; }
.tt input, .tt-extra input { width: 100%; min-width: 64px; font: inherit; font-family: var(--font-m); color: var(--text); background: var(--code-bg); border: 1.5px solid var(--border-2); border-radius: 7px; padding: 5px 8px; }
.tt input.ok, .tt-extra input.ok { border-color: var(--ok); background: var(--ok-bg); color: var(--ok); font-weight: 700; }
.tt input.bad, .tt-extra input.bad { border-color: var(--bad); background: var(--bad-bg); color: var(--bad); }
.tt-fix { display: block; margin-top: 3px; font-size: 12.5px; color: var(--ok); font-weight: 700; }
.tt-fix::before { content: "→ "; }
.tt-extra { display: flex; align-items: center; gap: 10px; margin-top: 12px; font-weight: 700; font-size: 14px; flex-wrap: wrap; }
.tt-extra input { width: auto; flex: 1 1 160px; max-width: 280px; }
/* code questions */
.q-ban { margin: 0 0 12px; font-size: 14px; }
.badge-nb { font-size: 10.5px; font-weight: 800; letter-spacing: .05em; text-transform: uppercase; color: #3A2E00; background: var(--a2); padding: 2px 8px; border-radius: 6px; margin-right: 6px; }
.q-editor { border: 1px solid var(--border); border-radius: var(--radius-sm); overflow: hidden; }
.q-editor .CodeMirror { height: auto; min-height: 180px; max-height: 460px; }
.q-editor .CodeMirror-scroll { min-height: 180px; max-height: 460px; }
.q-tests { margin-top: 14px; padding: 12px 14px; border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--surface-2); }
.q-tests h4 { display: flex; justify-content: space-between; font-size: 12px; text-transform: uppercase; letter-spacing: .09em; color: var(--faint); font-family: var(--font-m); margin-bottom: 6px; }
.q-tests ul { list-style: none; margin: 0; padding: 0; }
.q-tests li { display: flex; gap: 9px; align-items: flex-start; padding: 7px 0; font-size: 14px; border-top: 1px dashed var(--border); line-height: 1.4; font-family: var(--font-m); }
.q-tests li:first-child { border-top: 0; }
.q-tests li .ic { margin-top: 1px; width: 18px; height: 18px; padding: 2px; border-radius: 50%; stroke-width: 3; }
.q-tests li.pass .ic { color: var(--ok); background: var(--ok-bg); }
.q-tests li.fail .ic { color: var(--bad); background: var(--bad-bg); }
.q-tests small { display: block; color: var(--bad); font-size: 12.5px; margin-top: 2px; word-break: break-word; }
.t-err { display: flex; gap: 8px; align-items: flex-start; color: var(--bad); font-family: var(--font-m); font-size: 13.5px; margin: 8px 0 0; }
.t-err .ic { margin-top: 2px; }
.t-run { color: var(--faint); margin: 0; }
.t-friendly { font-size: 14px; margin: 6px 0 0; }
.q-hint { margin-top: 12px; padding: 12px 14px; border-radius: var(--radius-sm); border: 1.5px dashed color-mix(in srgb, var(--a2) 70%, var(--border)); font-size: 14.5px; }
.q-solution { margin-top: 12px; }
.q-model summary { cursor: pointer; font-weight: 700; color: var(--ink); }
/* written answers */
.q-ms { margin-top: 14px; }
.ms-list { list-style: none; margin: 0; padding: 0; display: grid; gap: 8px; }
.ms-list label { display: flex; gap: 10px; align-items: flex-start; padding: 10px 12px; border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--surface-2); cursor: pointer; line-height: 1.45; font-size: 14.5px; }
.ms-list input { width: 18px; height: 18px; margin-top: 2px; accent-color: var(--ok); flex: none; }
.q-model-note { margin-top: 10px; font-size: 14px; color: var(--muted); }
.ms-score { font-family: var(--font-m); font-weight: 700; }
/* flowcharts & UML */
.flowchart { display: block; max-width: 100%; height: auto; margin: 0 auto; font-family: var(--font-m); }
.fc-term { fill: var(--surface-2); stroke: var(--text); stroke-width: 1.6; }
.fc-proc { fill: var(--surface); stroke: var(--text); stroke-width: 1.6; }
.fc-io { fill: color-mix(in srgb, var(--a1) 9%, var(--surface)); stroke: var(--text); stroke-width: 1.6; }
.fc-dec { fill: color-mix(in srgb, var(--hl) 35%, var(--surface)); stroke: var(--text); stroke-width: 1.6; }
.fc-line { fill: none; stroke: var(--muted); stroke-width: 1.6; }
.fc-head { fill: var(--muted); }
.fc-text { font-size: 13px; fill: var(--text); text-anchor: middle; }
.fc-label { font-size: 12px; font-weight: 700; fill: var(--ink); font-family: var(--font-b); }
.uml { display: inline-block; min-width: 240px; border: 2px solid var(--text); border-radius: 4px; background: var(--surface); font: 14px/1.6 var(--font-m); }
.uml-name { text-align: center; font-weight: 700; padding: 6px 12px; border-bottom: 2px solid var(--text); font-family: var(--font-b); }
.uml-sec { padding: 6px 12px; min-height: 30px; }
.uml-sec + .uml-sec { border-top: 2px solid var(--text); }
@media (max-width: 780px) {
  .q-card { padding: 18px 16px; }
  .q-kind { margin-left: 0; width: 100%; }
  .why { margin-left: 8px; }
}

/* ================= MY QUESTIONS ================= */
.mini-link { display: inline-flex; align-items: center; gap: 6px; margin-top: 12px; font-size: 13.5px; font-weight: 700; color: var(--ink); text-decoration: none; }
.mini-link:hover { text-decoration: underline; }
.mini-link .ic { width: 15px; height: 15px; }
.rv-tools { display: flex; flex-wrap: wrap; align-items: flex-end; gap: 12px 16px; padding: 14px 16px; margin: 4px 0 16px; }
.rv-field { display: flex; flex-direction: column; gap: 4px; font-size: 12px; font-weight: 700; letter-spacing: .06em; text-transform: uppercase; color: var(--faint); font-family: var(--font-m); flex: 1 1 200px; }
.rv-field select { font: 15px var(--font-b); text-transform: none; letter-spacing: 0; color: var(--text); background: var(--surface-2); border: 1.5px solid var(--border-2); border-radius: var(--radius-sm); padding: 8px 10px; }
.seg { display: flex; gap: 4px; padding: 4px; border: 1px solid var(--border); border-radius: 12px; background: var(--surface-2); flex-wrap: wrap; }
.seg-b { display: flex; align-items: center; gap: 6px; padding: 7px 12px; border-radius: 9px; font-size: 14px; font-weight: 700; color: var(--muted); text-decoration: none; }
.seg-b b { font-family: var(--font-m); font-size: 12px; padding: 0 6px; border-radius: 6px; background: var(--surface); }
.seg-b .ic { width: 14px; height: 14px; stroke-width: 3; }
.seg-b.on { background: var(--surface); color: var(--text); box-shadow: inset 0 0 0 1.5px var(--border-2); }
.seg-b.bad .ic { color: var(--bad); } .seg-b.ok .ic { color: var(--ok); }
.rv-list { list-style: none; margin: 0; padding: 0; display: grid; gap: 10px; }
.rv-item { display: flex; align-items: center; gap: 14px; padding: 14px 16px; text-decoration: none; border-left: 5px solid var(--border-2); transition: transform .12s, border-color .15s; }
.rv-item:hover { transform: translateX(2px); }
.rv-item.st-wrong, .rv-item.st-part { border-left-color: var(--bad); }
.rv-item.st-right { border-left-color: var(--ok); }
.rv-item.st-fixed { border-left-color: var(--a1); }
.rv-st { width: 32px; height: 32px; flex: none; display: grid; place-items: center; border-radius: 50%; }
.rv-st .ic { width: 18px; height: 18px; stroke-width: 3; }
.st-wrong .rv-st, .st-part .rv-st { background: var(--bad-bg); color: var(--bad); }
.st-right .rv-st { background: var(--ok-bg); color: var(--ok); }
.st-fixed .rv-st { background: color-mix(in srgb, var(--a1) 15%, transparent); color: var(--ink); }
.rv-main { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 3px; }
.rv-top { display: flex; flex-wrap: wrap; align-items: baseline; gap: 4px 10px; font-weight: 700; font-size: 14.5px; }
.rv-top code { font-family: var(--font-m); font-size: 12px; color: var(--ink); }
.rv-kind { font-weight: 400; font-size: 13px; color: var(--faint); }
.rv-prev { font-size: 14px; color: var(--muted); overflow: hidden; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; line-height: 1.45; }
.rv-side { display: flex; flex-direction: column; align-items: flex-end; gap: 1px; flex: none; text-align: right; }
.rv-side b { font-family: var(--font-m); font-size: 14px; }
.rv-side small { font-size: 12px; color: var(--faint); white-space: nowrap; }
.rv-more { margin-top: 14px; display: flex; justify-content: center; }
.rv-empty { padding: 22px; text-align: center; color: var(--muted); }
.rv-badge.st-wrong, .rv-badge.st-part { color: var(--bad); border-color: color-mix(in srgb, var(--bad) 40%, transparent); background: var(--bad-bg); }
.rv-badge.st-right { color: var(--ok); border-color: color-mix(in srgb, var(--ok) 40%, transparent); background: var(--ok-bg); }
.rv-badge.st-fixed { color: var(--ink); border-color: color-mix(in srgb, var(--a1) 40%, transparent); background: color-mix(in srgb, var(--a1) 12%, transparent); }
.rv-badge .ic { stroke-width: 3; }
.rv-attempts { list-style: none; margin: 14px 0 0; padding: 0; display: flex; flex-wrap: wrap; gap: 8px; }
.rv-attempts li { display: flex; align-items: center; gap: 6px; font-size: 12.5px; font-weight: 700; padding: 5px 10px; border-radius: 9px; border: 1px solid var(--border); background: var(--surface); }
.rv-attempts li .ic { width: 14px; height: 14px; stroke-width: 3; }
.rv-attempts li.ok .ic { color: var(--ok); } .rv-attempts li.bad .ic { color: var(--bad); }
.q-banner { display: flex; align-items: center; gap: 8px; margin: -6px 0 14px; padding: 9px 12px; border-radius: var(--radius-sm); background: color-mix(in srgb, var(--hl) 45%, transparent); font-size: 14px; font-weight: 700; }
.q-banner .ic { flex: none; color: var(--ink); }
.rd-prog { height: 8px; margin-top: 14px; border-radius: 9px; background: var(--surface-2); box-shadow: inset 0 0 0 1px var(--border); overflow: hidden; }
.rd-prog i { display: block; height: 100%; width: 0; background: linear-gradient(90deg, var(--a1), var(--ok)); transition: width .4s; }
.rd-done { padding: 26px; text-align: center; }
.rd-done .h2 { justify-content: center; }
.rd-done .hero-actions { justify-content: center; }
@media (max-width: 640px) {
  .rv-item { flex-wrap: wrap; gap: 10px; }
  .rv-side { flex-direction: row; gap: 10px; width: 100%; justify-content: flex-start; padding-left: 46px; }
}

/* ================= REASONING PANELS ================= */
.q-why { margin-top: 14px; border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--surface); }
.q-why > summary { cursor: pointer; display: flex; align-items: center; gap: 8px; padding: 10px 14px; font-size: 14.5px; list-style: none; }
.q-why > summary::-webkit-details-marker { display: none; }
.q-why > summary .ic { color: var(--ink); }
.q-why > summary b { font-family: var(--font-h); font-size: 21px; color: var(--ink); font-weight: 700; }
.q-why[open] > summary { border-bottom: 1px dashed var(--border); }
.q-why-body { padding: 12px 14px 14px; }
.q-why-body > :first-child { margin-top: 0; }
.q-steps-n { margin: 0 0 10px; padding-left: 22px; display: grid; gap: 6px; }
.q-steps-n li { line-height: 1.5; }
.q-steps-n code, .q-diff code, .q-why-body p code, .t-diag code { font-family: var(--font-m); font-size: .86em; padding: .05em .35em; border-radius: 5px; background: var(--surface-2); border: 1px solid var(--border); color: var(--ink); }
.tv-help { font-size: 13.5px; color: var(--muted); margin: 6px 0 8px; }
.tv-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: var(--radius-sm); margin: 6px 0 10px; }
.tv, .diff { width: 100%; border-collapse: collapse; font-size: 13.5px; }
.tv th, .diff th { text-align: left; font: 700 11.5px var(--font-m); letter-spacing: .06em; text-transform: uppercase; color: var(--faint); padding: 7px 10px; background: var(--surface-2); border-bottom: 1px solid var(--border); white-space: nowrap; }
.tv td, .diff td { padding: 6px 10px; border-bottom: 1px solid var(--border); vertical-align: top; }
.tv tr:last-child td, .diff tr:last-child td { border-bottom: 0; }
.tv tr[data-line] { cursor: pointer; }
.tv tr[data-line]:hover { background: var(--surface-2); }
.tv .tv-i, .tv .tv-l { font: 12px var(--font-m); color: var(--faint); width: 1%; white-space: nowrap; }
.tv .tv-l { color: var(--ink); font-weight: 700; }
.tv .tv-code code { font: 13px/1.5 var(--font-m); white-space: pre; display: block; }
.tv tr.d2 .tv-code code { border-left: 3px solid color-mix(in srgb, var(--a3) 45%, transparent); }
.tv tr.d3 .tv-code code { border-left: 3px solid color-mix(in srgb, var(--a3) 75%, transparent); }
.tv tr.syn { background: color-mix(in srgb, var(--hl) 14%, transparent); }
.tv .tv-what { min-width: 160px; line-height: 1.7; }
.tv .tv-out pre { margin: 0; font: 13px/1.5 var(--font-m); white-space: pre-wrap; color: var(--text); }
.tv-chg { display: inline-block; font: 12.5px var(--font-m); padding: 0 6px; margin: 1px 4px 1px 0; border-radius: 5px; background: color-mix(in srgb, var(--a1) 12%, transparent); border: 1px solid color-mix(in srgb, var(--a1) 30%, transparent); }
.tv-chg b { color: var(--ink); }
.tv-cond { font: 700 12px var(--font-m); padding: 0 6px; border-radius: 5px; }
.tv-cond.t { background: var(--ok-bg); color: var(--ok); } .tv-cond.f { background: var(--bad-bg); color: var(--bad); }
.tv-note { color: var(--muted); font-style: italic; }
.q-code .l.hl { background: color-mix(in srgb, var(--hl) 45%, transparent); }
.diff code { font: 13px var(--font-m); white-space: pre-wrap; }
.diff tr.first { background: var(--bad-bg); }
.diff tr.first td:first-child { box-shadow: inset 3px 0 0 var(--bad); font-weight: 700; }
.diff tr.differ { background: color-mix(in srgb, var(--bad-bg) 50%, transparent); }
.t-diag { display: block; margin-top: 6px; padding: 8px 10px; border-radius: 8px; background: var(--surface); border: 1px dashed var(--border-2); font-family: var(--font-b); font-size: 13.5px; line-height: 1.5; color: var(--text); }
.ann { border: 1px solid var(--border); border-radius: var(--radius-sm); overflow: hidden; background: var(--code-bg); }
.ann-row { display: grid; grid-template-columns: 2.4em minmax(0, 1.05fr) minmax(0, 1fr); align-items: start; border-bottom: 1px solid var(--border); }
.ann-row:last-child { border-bottom: 0; }
.ann-row.blank { min-height: 10px; }
.ann-n { font: 12px/1.7 var(--font-m); color: var(--code-ln); text-align: right; padding: 4px 8px 4px 0; user-select: none; }
.ann-code { font: 13px/1.7 var(--font-m); white-space: pre; overflow-x: auto; padding: 4px 10px 4px 0; color: var(--code-text); background: none; border: 0; }
.ann-code .cm-keyword { color: var(--tk-kw); font-weight: 700; } .ann-code .cm-string { color: var(--tk-str); } .ann-code .cm-number { color: var(--tk-num); }
.ann-code .cm-builtin, .ann-code .cm-def { color: var(--tk-fn); } .ann-code .cm-comment { color: var(--code-com); font-style: italic; }
.ann-note { font-size: 13.5px; line-height: 1.5; padding: 5px 12px; color: var(--muted); border-left: 1px dashed var(--border-2); background: var(--surface); }
.tv-code .cm-keyword, .q-steps-n .cm-keyword { color: var(--tk-kw); font-weight: 700; } .tv-code .cm-string { color: var(--tk-str); } .tv-code .cm-number { color: var(--tk-num); } .tv-code .cm-builtin { color: var(--tk-fn); }
.ms-why { display: block; margin-top: 4px; font-size: 13px; color: var(--muted); line-height: 1.45; }
.ms-why b { color: var(--ink); }
.model-ans { padding: 12px 14px; border-radius: var(--radius-sm); background: var(--surface-2); border: 1px solid var(--border); line-height: 1.6; }
.model-ans p { margin: 0 0 8px; } .model-ans p:last-child { margin: 0; }
.model-ans .mk { font: 700 12px var(--font-m); color: var(--ok); background: var(--ok-bg); padding: 0 5px; border-radius: 5px; margin-left: 3px; white-space: nowrap; }
@media (max-width: 640px) {
  .ann-row { grid-template-columns: 2.2em minmax(0, 1fr); }
  .ann-note { grid-column: 2; border-left: 0; border-top: 1px dashed var(--border-2); }
}
.tv .tv-code code { background: none; border: 0; padding: 0 0 0 0; color: var(--code-text); }
.tv .tv-code code[style] { padding-right: 0; }
.q-feedback .ann-code, .q-solution .ann-code, .ann .ann-code { background: none; border: 0; border-radius: 0; padding: 4px 10px 4px 0; color: var(--code-text); }

/* ===== "Build it from scratch" notes (widgets/notes.js) ===== */
.notes > p { max-width: 68ch; }
.nt-toc { margin: 4px 0 8px; padding: 12px 16px; border: 1px dashed var(--border-2); border-radius: var(--radius-sm); background: var(--surface-2); }
.nt-toc ol { margin: 6px 0 0; padding-left: 22px; }
.nt-toc li { margin: 3px 0; }
.nt-toc a { color: var(--ink); font-weight: 700; }
.nt-prog { margin-top: 30px; padding-top: 22px; border-top: 2px solid var(--border); scroll-margin-top: calc(var(--top-h) + 16px); }
.nt-title { display: flex; flex-wrap: wrap; align-items: baseline; gap: 4px 10px; font-size: 22px !important; line-height: 1.25; }
.nt-pn { font: 700 12px var(--font-m); letter-spacing: .06em; text-transform: uppercase; color: var(--ink); background: color-mix(in srgb, var(--a1) 12%, transparent); border: 1px solid color-mix(in srgb, var(--a1) 30%, transparent); padding: 2px 8px; border-radius: 999px; }
.nt-h { display: flex; align-items: center; gap: 9px; font-family: var(--font-d); font-size: 16px; font-weight: 800; margin: 24px 0 10px; }
.nt-hn { display: inline-grid; place-items: center; width: 24px; height: 24px; flex: none; border-radius: 50%; background: var(--a1); color: #fff; font: 700 12.5px var(--font-m); }
.nt-io { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 8px; margin: 10px 0 0; }
.nt-io div { padding: 9px 12px; border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--surface-2); }
.nt-io dt { font: 700 11.5px var(--font-m); letter-spacing: .06em; text-transform: uppercase; color: var(--faint); }
.nt-io dd { margin: 2px 0 0; }
.nt-think { margin: 0 0 10px; padding-left: 22px; max-width: 72ch; }
.nt-think li { margin: 6px 0; }
.nt-works, .nt-tnote { max-width: 72ch; padding: 9px 12px; border-left: 3px solid var(--a1); background: color-mix(in srgb, var(--a1) 6%, transparent); border-radius: 0 8px 8px 0; }
.nt-help { font-size: 13.5px; color: var(--muted); margin: 0 0 8px !important; }
.nt-vars td:first-child { width: 1%; white-space: nowrap; }
.nt-vars td:nth-child(2) { width: 1%; white-space: nowrap; font: 13px var(--font-m); color: var(--muted); }
.nt-code .l.new { background: color-mix(in srgb, var(--hl) 50%, transparent); box-shadow: inset 3px 0 0 var(--a2); }
.nt-code .l.dim { color: var(--code-com); font-style: italic; }
.nt-code .l.dim span { color: inherit !important; font-weight: 400 !important; }
.nt-code .l.bad { background: var(--bad-bg); box-shadow: inset 3px 0 0 var(--bad); }
.nt-build { border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface-2); padding: 12px; }
.nt-bnav { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }
.nt-bpos { font: 700 13px var(--font-m); color: var(--ink); min-width: 9.5em; text-align: center; }
.nt-ball { margin-left: auto; }
.nt-bsteps { list-style: none; margin: 0; padding: 0; }
.nt-bstep { margin-top: 10px; }
.nt-build.all .nt-bstep { padding-top: 12px; border-top: 1px dashed var(--border-2); }
.nt-build.all .nt-bstep:first-child { border-top: 0; padding-top: 0; }
.nt-bk { font-size: 13.5px; font-weight: 700; margin: 0 !important; overflow-wrap: anywhere; }
.nt-bwhy { margin-top: 10px; }
.nt-bwhy p { margin: 0 0 6px !important; }
.nt-miss { color: var(--muted); }
.nt-miss b { color: var(--bad); }
.nt-run { margin-top: 10px; }
.nt-final { margin-top: 12px; border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--surface); padding: 10px 12px; }
.nt-final > summary { cursor: pointer; font-weight: 700; }
.nt-typed { font-size: 13.5px; color: var(--muted); margin: 8px 0 0 !important; }
.nt-typed kbd { font: 12.5px var(--font-m); padding: 1px 6px; border-radius: 5px; border: 1px solid var(--border-2); background: var(--surface); color: var(--text); }
.nt-res { margin-top: 10px; border-radius: var(--radius-sm); font-size: 14px; }
.nt-res.out { border: 1px solid var(--border); background: var(--con-bg); overflow: hidden; }
.nt-res-k { display: block; font: 700 11px var(--font-m); letter-spacing: .06em; text-transform: uppercase; color: var(--faint); padding: 6px 12px 0; }
.nt-res pre { margin: 0; padding: 4px 12px 10px; font: 13px/1.6 var(--font-m); white-space: pre-wrap; color: var(--text); }
.nt-res.err, .nt-res.loops { display: flex; gap: 8px; align-items: flex-start; padding: 9px 12px; background: var(--bad-bg); color: var(--text); border: 1px solid color-mix(in srgb, var(--bad) 30%, transparent); }
.nt-res .ic { color: var(--bad); flex: none; margin-top: 2px; }
.nt-mistakes { display: grid; gap: 14px; }
.nt-mis { border: 1px solid var(--border); border-radius: var(--radius); padding: 12px 14px; background: var(--surface); }
.nt-mis h5 { display: flex; align-items: center; gap: 7px; font-size: 15px; margin: 0; font-family: var(--font-d); }
.nt-mis h5 .ic { color: var(--bad); }
.nt-mis > p { margin: 10px 0 0 !important; max-width: 72ch; }
.nt-changes { padding-left: 22px; max-width: 72ch; }
.nt-changes li { margin: 6px 0; }
.nt-tip { display: flex; gap: 10px; align-items: flex-start; padding: 12px 14px; border-radius: var(--radius-sm); background: color-mix(in srgb, var(--hl) 22%, var(--surface)); border: 1px solid color-mix(in srgb, var(--a2) 55%, var(--border)); max-width: 76ch; }
.nt-tip > .ic { flex: none; margin-top: 2px; color: var(--ink); }
.nt-ttable tr.on { background: color-mix(in srgb, var(--hl) 30%, transparent); }
.nt-ttable td.nt-cell { white-space: nowrap; }
@media (max-width: 640px) {
  .nt-ball { margin-left: 0; }
  .nt-bpos { min-width: 0; }
  .nt-title { font-size: 19px !important; }
}
.nt-ttable td { padding: 4px 8px; }
.nt-ttable td:nth-last-child(2) { white-space: nowrap; }
.nt-ttable code { padding: 0 .3em; }

/* The `font` shorthand (used on code blocks) resets ligature settings, so switch them off on every element:
   code must show >= and != exactly as typed, never as ≥ or ≠. */
*, *::before, *::after { font-variant-ligatures: none; font-feature-settings: 'calt' 0, 'liga' 0; }
.nt-chart { margin: 14px 0; overflow-x: auto; text-align: center; }
.nt-chart .flowchart { max-width: 100%; height: auto; }
.nt-spec th { width: 1%; white-space: nowrap; text-align: left; vertical-align: top; text-transform: none; letter-spacing: 0; font: 700 13px var(--font-b); color: var(--ink); background: var(--surface-2); border-bottom: 1px solid var(--border); }

/* Notes at phone width: grid/flex children must be allowed to shrink, so long code lines scroll inside their own
   box (.q-code has overflow-x: auto) instead of stretching the page. */
.nt-mistakes { grid-template-columns: minmax(0, 1fr); }
.nt-prog, .nt-mis, .nt-bstep, .nt-build, .nt-final, .nt-tracebox, .nt-tip > div, .nt-res > span, .nt-io > div { min-width: 0; }
.nt-res > span, .nt-bk, .nt-mis h5, .nt-typed, .nt-io dd { overflow-wrap: anywhere; }
.nt-res pre { overflow-x: auto; }

/* ===== Lesson tabs filled with practice questions (widgets/lessonq.js) ===== */
.lq-head { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 8px 14px; margin: 0 0 10px; }
.lq-help { margin: 0; font-size: 14px; color: var(--muted); max-width: 62ch; }
.lq-bar { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.lq-score { font: 700 12.5px var(--font-m); color: var(--ink); }
.lq-list { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: minmax(0, 1fr); gap: 18px; }
.lq-item { min-width: 0; }
.lq-num { font: 700 11.5px var(--font-m); letter-spacing: .06em; text-transform: uppercase; color: var(--faint); margin: 0 0 6px 2px; }
.lq-card .q-card { margin: 0; }
.lq-more { margin: 14px 0 0; }
.link-btn { border: 0; background: none; padding: 0; font: inherit; font-weight: 700; color: var(--ink); text-decoration: underline; cursor: pointer; }

/* ===== Step mode (widgets/stepper.js) ===== */
.pg-step { border-top: 1px solid var(--border); background: var(--surface); padding: 10px 12px; max-height: 46%; overflow: auto; flex: none; }
.playground.is-stepping .pg-editor { box-shadow: inset 3px 0 0 var(--a3); }
.step-bar { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; }
.step-pos { font: 700 12.5px var(--font-m); color: var(--ink); margin: 0 4px; }
.step-exit { margin-left: auto; }
.step-say { margin: 8px 0 4px; font-size: 13.5px; line-height: 1.5; }
.step-say p { margin: 0 0 4px; }
.step-say code, .step-vars code { font: 12.5px var(--font-m); }
.step-k { display: inline-block; font: 700 10.5px var(--font-m); letter-spacing: .06em; text-transform: uppercase; padding: 1px 6px; border-radius: 5px; margin-right: 6px; background: var(--surface-2); border: 1px solid var(--border); color: var(--muted); }
.step-next .step-k { background: color-mix(in srgb, var(--a3) 18%, transparent); color: var(--text); border-color: transparent; }
.step-next.done .step-k { background: var(--ok-bg); color: var(--ok); }
.step-next.err .step-k { background: var(--bad-bg); color: var(--bad); }
.step-frame { font-size: 12px; color: var(--muted); font-style: italic; }
.step-frame-label { font: 700 11px var(--font-m); letter-spacing: .06em; text-transform: uppercase; color: var(--faint); margin: 8px 0 4px; }
.step-vars { width: 100%; border-collapse: collapse; font-size: 13px; }
.step-vars th { text-align: left; font: 700 11px var(--font-m); color: var(--faint); padding: 4px 8px; border-bottom: 1px solid var(--border); }
.step-vars td { padding: 4px 8px; border-bottom: 1px solid var(--border); vertical-align: top; overflow-wrap: anywhere; }
.step-vars td:first-child { width: 1%; white-space: nowrap; }
.step-vars tr.chg { background: color-mix(in srgb, var(--hl) 35%, transparent); }
.step-none, .step-help { font-size: 12.5px; color: var(--muted); margin: 6px 0 0; }
.step-intro p { margin: 0 0 8px; font-size: 13.5px; }
.step-inputs { width: 100%; font: 13px var(--font-m); padding: 6px 8px; border-radius: 8px; border: 1px solid var(--border-2); background: var(--code-bg); color: var(--code-text); margin-bottom: 8px; }
.CodeMirror .cm-stepnext { background: color-mix(in srgb, var(--a3) 22%, transparent); }
.CodeMirror .cm-stepran { background: color-mix(in srgb, var(--hl) 22%, transparent); }
.CodeMirror .cc-bp { width: 14px; cursor: pointer; }
.cc-bp-dot { display: block; width: 9px; height: 9px; margin: 5px 0 0 3px; border-radius: 50%; background: var(--bad); }
.CodeMirror-linenumber { cursor: pointer; }
.dock .playground.is-stepping .pg-console { flex-basis: 20%; }
.dock .pg-step { max-height: 48%; }
.step-t { color: var(--ok); } .step-f { color: var(--bad); }
.pg-step .step-bar { position: sticky; top: -10px; z-index: 2; background: var(--surface); padding: 2px 0 6px; margin-top: -2px; }
.pg-step { padding-top: 10px; }

/* ===== Visualizers (widgets/viz-*.js) ===== */
.viz { margin: 16px 0 6px; padding: 14px 16px; border: 1px solid var(--border); border-radius: var(--radius); background: var(--surface-2); min-width: 0; }
.viz-head h4 { margin: 2px 0 4px; font-family: var(--font-d); font-size: 16px; }
.viz-head p { margin: 0 0 10px !important; font-size: 13.5px; color: var(--muted); max-width: 72ch; }
.viz-tag { display: inline-flex; align-items: center; gap: 5px; font: 700 11px var(--font-m); letter-spacing: .06em; text-transform: uppercase; color: var(--ink); }
.viz-tag .ic { width: 13px; height: 13px; }
.viz-controls, .viz-player { display: flex; flex-wrap: wrap; align-items: center; gap: 6px 8px; margin: 6px 0; }
.viz-field { display: inline-flex; align-items: center; gap: 6px; font-size: 13px; font-weight: 700; color: var(--muted); }
.viz-field input[type=text], .viz-field input[type=number], .viz-field select { font: 13px var(--font-m); padding: 5px 7px; border-radius: 8px; border: 1px solid var(--border-2); background: var(--surface); color: var(--text); min-width: 0; }
.viz-field input[type=number] { width: 4.5em; }
.viz-field input[type=text] { width: 8em; }
.viz-wide { flex: 1 1 260px; } .viz-wide input[type=text] { width: 100%; }
.viz-check { display: inline-flex; align-items: center; gap: 5px; font-size: 13px; }
.viz-stage { margin: 10px 0 6px; overflow-x: auto; }
.viz-say { margin: 6px 0 !important; font-size: 14px; line-height: 1.55; min-height: 1.5em; }
.viz-bad { color: var(--bad); }
.viz-state { display: flex; flex-wrap: wrap; gap: 4px 16px; font-size: 13px; margin-top: 8px; }
.viz-legend { display: flex; flex-wrap: wrap; align-items: center; gap: 4px 8px; font-size: 12px; color: var(--muted); width: 100%; margin-top: 4px; }
.viz-legend .lg { display: inline-block; width: 12px; height: 12px; border-radius: 3px; border: 1px solid var(--border-2); margin-left: 6px; }
.lg.live, .lg.in { background: color-mix(in srgb, var(--a1) 22%, var(--surface)); }
.lg.ghost { background: var(--surface); border-style: dashed; }
.lg.cmp { background: color-mix(in srgb, var(--a3) 45%, var(--surface)); }
.lg.swap { background: color-mix(in srgb, var(--hl) 75%, var(--surface)); }
.lg.done { background: var(--ok-bg); border-color: var(--ok); }
.lg.min { background: var(--surface); border: 2px solid var(--a3); }
.viz-idx { font: 11px var(--font-m); color: var(--faint); }
.viz-val { font: 700 14px var(--font-m); color: var(--text); }
.stack-col { display: inline-flex; flex-direction: column; gap: 4px; }
.viz-slot { display: grid; grid-template-columns: 2.6em 7em auto; align-items: center; gap: 8px; }
.viz-slot .viz-val, .viz-cell .viz-val { display: grid; place-items: center; min-height: 34px; border: 1px solid var(--border-2); border-radius: 8px; background: var(--surface); padding: 0 6px; }
.viz-slot.live .viz-val, .viz-cell.live .viz-val, .viz-cell.in .viz-val { background: color-mix(in srgb, var(--a1) 22%, var(--surface)); border-color: color-mix(in srgb, var(--a1) 55%, transparent); }
.viz-slot.ghost .viz-val, .viz-cell.ghost .viz-val { color: var(--faint); border-style: dashed; }
.viz-slot.flash .viz-val, .viz-cell.flash .viz-val { box-shadow: 0 0 0 3px color-mix(in srgb, var(--hl) 70%, transparent); }
.viz-ptr { font: 700 12.5px var(--font-m); color: var(--ink); }
.queue-row, .bs-row { display: flex; gap: 4px; min-width: max-content; }
.viz-cell { display: flex; flex-direction: column; align-items: center; gap: 2px; min-width: 3.2em; }
.viz-cell .viz-val { width: 100%; }
.viz-cell.out .viz-val { opacity: .35; }
.viz-cell.mid .viz-val { border: 2px solid var(--a3); background: color-mix(in srgb, var(--a3) 22%, var(--surface)); }
.viz-cell.found .viz-val { border: 2px solid var(--ok); background: var(--ok-bg); }
.viz-marks { min-height: 18px; display: flex; gap: 2px; }
.viz-mk { font: 700 10.5px var(--font-m); padding: 0 5px; border-radius: 5px; background: var(--surface); border: 1px solid var(--border-2); color: var(--text); }
.viz-mk.front, .viz-mk.low { background: color-mix(in srgb, var(--a1) 25%, var(--surface)); }
.viz-mk.rear, .viz-mk.high { background: color-mix(in srgb, var(--hl) 60%, var(--surface)); }
.viz-mk.mid { background: color-mix(in srgb, var(--a3) 30%, var(--surface)); }
.viz-counters { display: flex; flex-wrap: wrap; gap: 6px; margin: 6px 0; }
.viz-count { font-size: 12.5px; padding: 3px 9px; border-radius: 999px; background: var(--surface); border: 1px solid var(--border); }
.viz-count b { font-family: var(--font-m); color: var(--ink); }
.viz-speed input { width: 90px; }
.viz-code { margin-top: 8px; }
.viz-code > summary { cursor: pointer; font-size: 13px; font-weight: 700; color: var(--ink); }
.viz-code .btn { margin-top: 8px; }
.viz-table td code { font: 12.5px var(--font-m); }
.sort-bars { display: flex; align-items: flex-end; gap: 4px; height: 180px; min-width: max-content; padding-top: 6px; }
.sort-bar { display: flex; flex-direction: column; align-items: center; justify-content: flex-end; height: 100%; width: 34px; gap: 2px; }
.sort-fill { width: 100%; border-radius: 4px 4px 0 0; background: color-mix(in srgb, var(--a1) 35%, var(--surface)); border: 1px solid color-mix(in srgb, var(--a1) 55%, transparent); transition: height .25s; }
.sort-bar.cmp .sort-fill { background: color-mix(in srgb, var(--a3) 55%, var(--surface)); border-color: var(--a3); }
.sort-bar.swap .sort-fill { background: color-mix(in srgb, var(--hl) 80%, var(--surface)); border-color: color-mix(in srgb, var(--a2) 80%, #000 10%); }
.sort-bar.done .sort-fill { background: var(--ok-bg); border-color: var(--ok); }
.sort-bar.min .sort-fill { outline: 2px solid var(--a3); outline-offset: 1px; }
.sort-v { font: 700 12px var(--font-m); color: var(--text); }
/* Big O chart: validated categorical slots (light / dark) */
.viz-bigo { --s1: #2a78d6; --s2: #eb6834; --s3: #1baf7a; --s4: #eda100; }
:root[data-mode=dark] .viz-bigo { --s1: #3987e5; --s2: #d95926; --s3: #199e70; --s4: #c98500; }
.viz-swatch { display: inline-block; width: 14px; height: 3px; border-radius: 2px; vertical-align: middle; margin-right: 5px; }
.viz-swatch.s1 { background: var(--s1); } .viz-swatch.s2 { background: var(--s2); } .viz-swatch.s3 { background: var(--s3); } .viz-swatch.s4 { background: var(--s4); }
.bigo-chart { position: relative; margin: 8px 0; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-sm); }
.bigo-chart:focus-visible { outline: 2px solid var(--a1); outline-offset: 2px; }
.bigo-chart svg { display: block; width: 100%; height: auto; }
.bigo-line { fill: none; stroke-width: 2; stroke-linejoin: round; stroke-linecap: round; }
.bigo-line.s1, .bigo-dot.s1 { stroke: var(--s1); } .bigo-line.s2, .bigo-dot.s2 { stroke: var(--s2); } .bigo-line.s3, .bigo-dot.s3 { stroke: var(--s3); } .bigo-line.s4, .bigo-dot.s4 { stroke: var(--s4); }
.bigo-dot { fill: var(--surface); stroke-width: 2; }
.bigo-dot.s1 { fill: var(--s1); } .bigo-dot.s2 { fill: var(--s2); } .bigo-dot.s3 { fill: var(--s3); } .bigo-dot.s4 { fill: var(--s4); }
.bigo-dot { stroke: var(--surface); }
.bigo-grid { stroke: var(--border); stroke-width: 1; }
.bigo-tick { font: 11px var(--font-m); fill: var(--faint); }
.bigo-axis { font: 12px var(--font-b); fill: var(--muted); }
.bigo-lab { font: 700 12px var(--font-m); fill: var(--text); }
.bigo-cross { stroke: var(--muted); stroke-width: 1; stroke-dasharray: 3 3; }
.bigo-hit { fill: transparent; cursor: crosshair; }
.bigo-tip { position: absolute; top: 8px; transform: translateX(-50%); display: flex; flex-direction: column; gap: 2px; padding: 6px 9px; border-radius: 8px; background: var(--surface); border: 1px solid var(--border-2); box-shadow: var(--shadow); font: 12px var(--font-m); color: var(--text); pointer-events: none; white-space: nowrap; }
.bigo-legend { display: flex; flex-direction: column; gap: 3px; font-size: 13px; color: var(--text); margin: 4px 0 8px; }
.viz-field { max-width: 100%; min-width: 0; }
.viz-field select { max-width: 12em; }