/* Science Wonders: shared look.
   Layout: an optics-bench notebook. A narrow reading column for prose,
   full-width "bench" panels for the live apparatus. */
:root {
  --paper: #eef1f5;
  --panel: #ffffff;
  --ink: #131c27;
  --ink-soft: #4a5868;
  --rule: #d3dae3;
  --accent: #2647c9;
  --accent-ink: #ffffff;
  --bench: #0d1420;        /* the apparatus is always viewed "in the dark room" */
  --bench-ink: #c9d4e3;
  --bench-rule: #26324a;
  --good: #1f8a5b;
  --warn: #b5562b;

  --font-display: "Spectral", "Iowan Old Style", Georgia, serif;
  --font-body: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, monospace;

  --step--1: 0.84rem;
  --step-0: 1rem;
  --step-1: 1.2rem;
  --step-2: 1.6rem;
  --step-3: 2.3rem;
  --step-4: 3.2rem;
  --radius: 10px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #0b1018;
    --panel: #121a26;
    --ink: #e4eaf2;
    --ink-soft: #97a6b9;
    --rule: #243045;
    --accent: #8fa6ff;
    --accent-ink: #0b1018;
    --bench: #05080e;
    --bench-ink: #c9d4e3;
    --bench-rule: #1f2a3f;
    --good: #4cc48d;
    --warn: #f08a5d;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #0b1018;
  --panel: #121a26;
  --ink: #e4eaf2;
  --ink-soft: #97a6b9;
  --rule: #243045;
  --accent: #8fa6ff;
  --accent-ink: #0b1018;
  --bench: #05080e;
  --bench-ink: #c9d4e3;
  --bench-rule: #1f2a3f;
  --good: #4cc48d;
  --warn: #f08a5d;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: var(--step-0);
  line-height: 1.6;
}
.wrap {
  max-width: 1080px;
  margin: 0 auto;
  padding-inline: 20px;
  padding-block: 0 64px;
}
h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: 600;
  line-height: 1.15;
  text-wrap: balance;
  margin: 0;
}
h1 { font-size: var(--step-4); letter-spacing: -0.01em; }
h2 { font-size: var(--step-2); }
h3 { font-size: var(--step-1); }
p { margin: 0; }
a { color: var(--accent); }
a:focus-visible, button:focus-visible, input:focus-visible, select:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}
.prose { max-width: 66ch; display: grid; gap: 0.9em; }
.eyebrow {
  font-family: var(--font-mono);
  font-size: var(--step--1);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-soft);
}
.muted { color: var(--ink-soft); }
code, .mono { font-family: var(--font-mono); font-size: 0.92em; }

/* Top bar */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding-block: 18px;
  border-bottom: 1px solid var(--rule);
  margin-bottom: 36px;
}
.brand {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: var(--step-1);
  color: var(--ink);
  text-decoration: none;
}
.brand span { color: var(--accent); }
.topbar nav { display: flex; gap: 18px; flex-wrap: wrap; font-size: var(--step--1); }
.topbar nav a { color: var(--ink-soft); text-decoration: none; }
.topbar nav a:hover, .topbar nav a[aria-current="page"] { color: var(--ink); }

/* Demo page header */
.demo-head { display: grid; gap: 12px; margin-bottom: 24px; }
.demo-head .lede { font-size: var(--step-1); color: var(--ink-soft); max-width: 60ch; }

/* The bench: dark apparatus panel */
.bench {
  background: var(--bench);
  color: var(--bench-ink);
  border-radius: var(--radius);
  padding: 14px;
  border: 1px solid var(--bench-rule);
}
.bench canvas { display: block; width: 100%; height: auto; border-radius: 6px; }

/* Controls */
.controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: 14px 22px;
  margin-top: 18px;
  padding: 18px;
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
}
.control { display: grid; gap: 4px; min-width: 0; }
.control label, .control .label {
  display: flex;
  justify-content: space-between;
  gap: 8px;
  font-size: var(--step--1);
  color: var(--ink-soft);
}
.control output, .readout {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  color: var(--ink);
}
input[type="range"] { width: 100%; accent-color: var(--accent); }
.button-row { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
button, .btn {
  font: inherit;
  font-size: var(--step--1);
  font-weight: 500;
  padding: 8px 14px;
  border-radius: 999px;
  border: 1px solid var(--rule);
  background: var(--panel);
  color: var(--ink);
  cursor: pointer;
}
button:hover { border-color: var(--ink-soft); }
button.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
button[aria-pressed="true"] { background: var(--ink); color: var(--paper); border-color: var(--ink); }

/* Toggle switch */
.control label.switch { justify-content: flex-start; }
.switch { display: inline-flex; align-items: center; gap: 10px; cursor: pointer; font-size: var(--step--1); }
.switch input { appearance: none; width: 38px; height: 22px; border-radius: 999px; background: var(--rule); position: relative; cursor: pointer; margin: 0; transition: background .15s; }
.switch input::after { content: ""; position: absolute; top: 3px; left: 3px; width: 16px; height: 16px; border-radius: 50%; background: var(--panel); transition: transform .15s; }
.switch input:checked { background: var(--accent); }
.switch input:checked::after { transform: translateX(16px); }

/* Explainer section */
.explain {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 28px;
  margin-top: 44px;
  padding-top: 28px;
  border-top: 1px solid var(--rule);
}
.explain section { display: grid; gap: 10px; align-content: start; min-width: 0; }
.explain ul { margin: 0; padding-left: 1.1em; display: grid; gap: 6px; }

/* Stat strip */
.stats { display: flex; flex-wrap: wrap; gap: 8px 26px; margin-top: 12px; font-size: var(--step--1); color: var(--ink-soft); }
.stats b { font-family: var(--font-mono); font-weight: 500; color: var(--ink); font-variant-numeric: tabular-nums; }

.footer { margin-top: 64px; padding-top: 18px; border-top: 1px solid var(--rule); font-size: var(--step--1); color: var(--ink-soft); }

@media (max-width: 560px) {
  h1 { font-size: var(--step-3); }
  .controls { padding: 14px; }
}
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; }
}

/* Real-world applications */
.apps { margin-top: 48px; display: grid; gap: 18px; }
.apps-head { display: grid; gap: 6px; }
.apps-head p { color: var(--ink-soft); max-width: 66ch; }
.apps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 0 28px;
  border-top: 1px solid var(--rule);
}
.app {
  display: grid;
  gap: 6px;
  align-content: start;
  padding-block: 18px;
  border-bottom: 1px solid var(--rule);
  min-width: 0;
}
.app p { font-size: 0.95rem; }
.app .link { font-size: var(--step--1); color: var(--ink-soft); }
.app .link b { color: var(--accent); font-weight: 600; }

/* ---------- Shared features (assets/wonders.js) ---------- */
.toolbar { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 10px; margin: -8px 0 18px; }
.toolbar .tool-link { font-size: var(--step--1); padding: 8px 6px; }
.tool-status { font-size: var(--step--1); color: var(--ink-soft); min-width: 0; flex: 1 1 220px; }
.share-box { width: 100%; font: inherit; font-family: var(--font-mono); font-size: 0.8rem; padding: 6px 8px; border: 1px solid var(--rule); border-radius: 6px; background: var(--panel); color: var(--ink); }

.predict {
  display: grid; gap: 10px; margin-bottom: 18px; padding: 18px 20px;
  background: var(--panel); border: 1px solid var(--rule); border-left: 3px solid var(--accent);
  border-radius: 0 var(--radius) var(--radius) 0;
}
.predict-q { font-family: var(--font-display); font-size: var(--step-1); font-weight: 600; max-width: 60ch; }
.predict-options { display: flex; flex-wrap: wrap; gap: 8px; }
.predict-options button { border-radius: var(--radius); text-align: left; max-width: 100%; }
.predict-skip { justify-self: start; border: 0; background: none; padding: 4px 0; color: var(--ink-soft); text-decoration: underline; }
.predict.answered { gap: 6px; }
.predict.right { border-left-color: var(--good); }
.predict.wrong { border-left-color: var(--warn); }
.predict-answer, .predict-try { max-width: 72ch; }
.bench-hidden { position: relative; }
.bench-hidden > * { filter: blur(10px) brightness(0.6); transition: filter .4s; pointer-events: none; }
.bench > * { transition: filter .4s; }

.quiz { margin-top: 48px; padding-top: 28px; border-top: 1px solid var(--rule); display: grid; gap: 18px; }
.quiz-item { display: grid; gap: 8px; max-width: 72ch; }
.quiz-options { display: flex; flex-wrap: wrap; gap: 8px; }
.quiz-options button { border-radius: var(--radius); text-align: left; max-width: 100%; }
.quiz-options button:disabled { cursor: default; opacity: 0.6; }
.quiz-options button.correct { opacity: 1; border-color: var(--good); box-shadow: inset 0 0 0 1px var(--good); }
.quiz-options button.incorrect { opacity: 1; border-color: var(--warn); box-shadow: inset 0 0 0 1px var(--warn); }
.quiz-why { font-size: 0.95rem; color: var(--ink-soft); min-height: 0; }
.quiz-why:empty { display: none; }
.quiz-score { font-weight: 600; }
.quiz-score:empty { display: none; }

.related { margin-top: 48px; display: grid; gap: 12px; }
.related-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 12px; }
.related-card {
  display: grid; gap: 4px; padding: 14px 16px; text-decoration: none; color: var(--ink);
  background: var(--panel); border: 1px solid var(--rule); border-radius: var(--radius); min-width: 0;
}
.related-card:hover { border-color: var(--accent); }
.related-card b { font-family: var(--font-display); font-size: var(--step-1); }
.related-card .muted { font-size: var(--step--1); }

.tour-bar {
  display: grid; gap: 8px; margin-bottom: 22px; padding: 14px 18px;
  background: var(--panel); border: 1px solid var(--accent); border-radius: var(--radius);
}
.tour-meta { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 6px 16px; }
.tour-meta a { text-decoration: none; color: var(--accent); }
.tour-goal { max-width: 72ch; }
.tour-nav { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 8px 16px; font-size: var(--step--1); font-weight: 500; }
.tour-next { margin-left: auto; }

/* Presenter mode: the apparatus and its controls fill the screen. */
.present-exit { display: none; }
.presenting body { background: var(--paper); }
.presenting .topbar, .presenting .demo-head .lede, .presenting .toolbar, .presenting .predict,
.presenting .callout, .presenting .explain, .presenting .apps, .presenting .quiz, .presenting .related,
.presenting .footer, .presenting .tour-bar { display: none !important; }
.presenting .wrap { max-width: none; padding-block: 16px; }
.presenting .demo-head { margin-bottom: 12px; }
.presenting .demo-head h1 { font-size: var(--step-3); }
.presenting .bench > * { filter: none; pointer-events: auto; }
.presenting .controls { font-size: 1.15rem; }
.presenting .controls button { font-size: 1rem; padding: 10px 18px; }
.presenting .stats { font-size: 1.05rem; }
.presenting .present-exit {
  display: block; position: fixed; z-index: 10; right: 16px;
  bottom: calc(16px + env(safe-area-inset-bottom, 0px));
}

/* Home page progress badges */
.badge { font-family: var(--font-mono); font-size: 0.72rem; letter-spacing: 0.04em; color: var(--good); }
a.btn { display: inline-block; text-decoration: none; }
.btn.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.lang-select { font: inherit; font-size: var(--step--1); padding: 4px 8px; border-radius: 999px; border: 1px solid var(--rule); background: var(--panel); color: var(--ink); }
.topbar nav { align-items: center; }
:lang(zh-CN) { --font-display: "Spectral", "Noto Serif SC", "Songti SC", "SimSun", serif; --font-body: "IBM Plex Sans", "PingFang SC", "Noto Sans SC", "Microsoft YaHei", system-ui, sans-serif; }
:lang(zh-CN) .eyebrow { letter-spacing: 0.04em; }