:root {
  --navy: #202D4A;
  --navy-2: #2D6687;
  --red: #F6C94C;
  --bg: #F4F8FB;
  --surface: #ffffff;
  --surface-2: #EAF2F8;
  --ink: #18243B;
  --muted: #59677A;
  --line: #DCE6EF;
  --accent: #2D6687;
  --accent-ink: #ffffff;
  --good: #2D7A60;
  --bad: #B84545;
  --warn: #e8590c;
  --c1: #0c8f7e;
  --c2: #e8590c;
  --c3: #7048e8;
  --c4: #1c7ed6;
  --c5: #0b7f95;
  --c6: #d6336c;
  --c7: #2f9e44;
  --c8: #e67700;
  --c9: #c92a2a;
  --scene: var(--accent);
  --dev: #2d3646;
  --dev-line: #586174;
  --screen: #d7e6fb;
  --shadow: 0 1px 2px rgb(20 25 40 / .06), 0 6px 20px rgb(20 25 40 / .07);
  --radius: 14px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --navy: #0c1b33;
    --navy-2: #172d52;
    --bg: #11151c;
    --surface: #1a1f29;
    --surface-2: #242a37;
    --ink: #e9ecf2;
    --muted: #9ba3b4;
    --line: #2f3646;
    --accent: #7fb6d8;
    --accent-ink: #0b1222;
    --good: #5fd27a;
    --bad: #ff6b9a;
    --warn: #ff922b;
    --c1: #2fc4ad;
    --c2: #ff8a3d;
    --c3: #9b7cff;
    --c4: #4dabf7;
    --c5: #3bc0d8;
    --c6: #f06595;
    --c7: #51cf66;
    --c8: #fcc419;
    --c9: #ff6b6b;
    --dev: #3a4457;
    --dev-line: #7a8498;
    --screen: #22406e;
    --shadow: none;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; font-size: 16px; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 1rem/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  padding-bottom: calc(5.2rem + env(safe-area-inset-bottom, 0px));
}
h1, h2, h3, h4 { line-height: 1.2; margin: 0; }
strong, b { font-weight: 650; }
button, select, textarea, input { font: inherit; color: inherit; }
button { cursor: pointer; }
button:disabled { cursor: default; }
code, .mono { font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace; font-size: .92em; }
code { background: var(--surface-2); padding: .05em .35em; border-radius: 5px; }
.small { font-size: .86rem; margin: .4rem 0 0; }
.muted { color: var(--muted); }
.good { color: var(--good); }
.bad { color: var(--bad); }
.mt { margin-top: 1.6rem; }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; border-radius: 6px; }

/* projector mode: everything scales with rem */
body.projector { --pj: 1; }
html:has(body.projector) { font-size: 19px; }

/* ---------- header ---------- */
.top { background: var(--navy); color: #fff; }
.top-inner {
  max-width: 1360px; margin: 0 auto;
  padding: .9rem 1.25rem .5rem;
  display: flex; align-items: center; justify-content: space-between; gap: 1rem; flex-wrap: wrap;
}
.brand { display: flex; align-items: center; gap: .9rem; min-width: 0; }
.logo {
  flex: none;
  display: block;
  width: 2.9rem; height: 2.9rem;
  background: url(/brand/mark-light.svg) center / contain no-repeat;
}
.logo:hover { filter: drop-shadow(0 0 8px rgb(246 201 76 / .6)); }
a.chip-btn { display: inline-flex; align-items: center; text-decoration: none; }
.kicker { margin: 0; font-size: .78rem; letter-spacing: .08em; text-transform: uppercase; opacity: .78; font-weight: 600; }
.brand h1 { font-size: clamp(1.3rem, 2.6vw, 1.9rem); letter-spacing: -.01em; }
.brand h1::after { content: ""; display: block; width: 2.6rem; height: 3px; background: var(--red); border-radius: 3px; margin-top: .35rem; }
.top-actions { display: flex; gap: .5rem; }
.chip-btn {
  border: 1px solid rgb(255 255 255 / .35); background: transparent; color: #fff;
  border-radius: 999px; padding: .35rem .85rem; font-size: .85rem;
}
.chip-btn:hover { background: rgb(255 255 255 / .1); }
.chip-btn[aria-pressed="true"] { background: #fff; color: var(--navy); border-color: #fff; font-weight: 650; }

.tabs {
  max-width: 1360px; margin: 0 auto;
  display: flex; gap: .35rem;
  overflow-x: auto; scrollbar-width: none;
  padding: .35rem 1.25rem .75rem;
}
.tabs::-webkit-scrollbar { display: none; }
.tabs button {
  flex: none;
  display: inline-flex; align-items: center; gap: .4rem;
  border: 1px solid rgb(255 255 255 / .18);
  background: rgb(255 255 255 / .06);
  color: rgb(255 255 255 / .82);
  border-radius: 999px;
  padding: .32rem .8rem .32rem .55rem;
  font-size: .86rem;
}
.tabs button .ic { width: 1.05rem; height: 1.05rem; }
.tabs button b { font-size: .72rem; opacity: .7; }
.tabs button:hover { background: rgb(255 255 255 / .14); }
.tabs button.active { background: #fff; color: var(--navy); border-color: #fff; font-weight: 650; }
.tabs button.active .ic { color: var(--c); }
@media (prefers-color-scheme: dark) { .tabs button.active .ic { color: var(--navy); } }

/* ---------- layout ---------- */
main { max-width: 1360px; margin: 0 auto; padding: 1rem 1.25rem 1.5rem; }
.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 1.1rem;
}
.lab {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(18rem, 22rem);
  gap: 1rem;
  align-items: start;
}
.side { display: grid; gap: 1rem; position: sticky; top: .8rem; }
.stage-card { border-top: 4px solid var(--scene); min-width: 0; }
.stage-head { display: flex; align-items: center; gap: .6rem; margin-bottom: .9rem; flex-wrap: wrap; }
.scene-ic { color: var(--scene); display: inline-flex; }
.scene-ic .ic { width: 1.7rem; height: 1.7rem; }
.stage-head h2 { font-size: 1.45rem; }
.try {
  margin-left: auto;
  font-size: .76rem; font-weight: 700; text-transform: uppercase; letter-spacing: .05em;
  color: var(--scene);
  background: color-mix(in srgb, var(--scene) 12%, var(--surface));
  border-radius: 999px; padding: .2rem .65rem;
}
.try-inline { font-size: .78em; font-weight: 700; color: var(--accent); background: color-mix(in srgb, var(--accent) 12%, var(--surface)); border-radius: 999px; padding: .05rem .5rem; }
.stage { min-height: 26rem; position: relative; }

.narration { min-height: 14rem; border-left: 4px solid var(--scene); }
.narration.enter { animation: enter .35s ease-out; }
@keyframes enter { from { opacity: .2; transform: translateY(6px); } }
.step-count { margin: 0 0 .25rem; font-size: .76rem; text-transform: uppercase; letter-spacing: .07em; color: var(--scene); font-weight: 700; }
.narration h3 { font-size: 1.25rem; margin-bottom: .55rem; }
.step-text p { margin: 0 0 .6rem; }
.step-text ul { margin: 0 0 .6rem; padding-left: 1.15rem; }
.step-text li { margin-bottom: .25rem; }
.tip {
  margin: .7rem 0 0; padding: .6rem .8rem;
  border-left: 4px solid var(--warn);
  background: color-mix(in srgb, var(--warn) 9%, var(--surface));
  border-radius: 0 8px 8px 0; font-size: .92rem;
}
.vocab h4 { font-size: .78rem; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); margin-bottom: .5rem; }
.vocab dl { margin: 0; display: grid; gap: .5rem; }
.vocab dt { font-weight: 700; color: var(--accent); }
.vocab dd { margin: 0; font-size: .9rem; color: var(--muted); }

@media (max-width: 960px) {
  .lab { grid-template-columns: minmax(0, 1fr); }
  .side { position: static; order: -1; }
  .narration { min-height: 0; }
  .vocab { display: none; }
  .stage { min-height: 0; }
}

/* ---------- controls ---------- */
.controls {
  position: fixed; left: 0; right: 0; bottom: 0; z-index: 20;
  display: flex; align-items: center; justify-content: center; gap: .5rem; flex-wrap: wrap;
  padding: .6rem 1rem calc(.75rem + env(safe-area-inset-bottom, 0px));
  background: color-mix(in srgb, var(--surface) 92%, transparent);
  backdrop-filter: blur(10px);
  border-top: 1px solid var(--line);
}
.btn {
  border: 1px solid var(--line); background: var(--surface);
  border-radius: 10px; padding: .5rem 1rem; font-weight: 600;
  display: inline-flex; align-items: center; gap: .35rem;
  transition: background .15s, transform .1s;
}
.btn:hover:not(:disabled) { background: var(--surface-2); }
.btn:active:not(:disabled) { transform: translateY(1px); }
.btn:disabled { opacity: .45; }
.btn.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); min-width: 7.5rem; justify-content: center; }
.btn.primary:hover:not(:disabled) { background: color-mix(in srgb, var(--accent) 86%, #000); }
.btn.ghost { background: transparent; }
.small-btn { padding: .35rem .75rem; font-size: .88rem; border-radius: 8px; }
.speed { font-size: .86rem; color: var(--muted); display: inline-flex; align-items: center; gap: .35rem; margin-left: .4rem; }
.speed select { border: 1px solid var(--line); border-radius: 8px; background: var(--surface); padding: .3rem .4rem; }
.progress { position: absolute; top: -1px; left: 0; right: 0; height: 3px; }
.progress div { height: 100%; width: 0; background: var(--scene); transition: width .4s; }
@media (max-width: 560px) {
  .btn span { display: none; }
  .speed { display: none; }
  .controls .btn { padding: .5rem .8rem; }
}

/* ---------- shared widgets ---------- */
.ic { width: 1.25rem; height: 1.25rem; flex: none; }
.dev { display: block; width: 100%; height: auto; overflow: visible; }
.dv-body { fill: var(--dev); }
.dv-screen { fill: var(--screen); }
.dv-detail { fill: var(--dev-line); }
.dv-unit { fill: color-mix(in srgb, var(--dev) 70%, #000); }
.dv-ring { fill: none; stroke: #74c0fc; stroke-width: 2; }
.dv-led { fill: #51cf66; }
.dv-lens { fill: #4dabf7; }
.dv-paper { fill: #f8f9fa; stroke: #ced4da; }
.dv-ink { stroke: #868e96; stroke-width: 2; }
.dv-cloud { fill: color-mix(in srgb, var(--c5) 22%, var(--surface)); stroke: var(--c5); stroke-width: 3; }
.dv-arrow { fill: none; stroke: var(--c5); stroke-width: 4; stroke-linecap: round; stroke-linejoin: round; }
.bp-body { fill: var(--c1); }
.bp-pocket { fill: color-mix(in srgb, var(--c1) 70%, #000); }
.bp-line { stroke: color-mix(in srgb, var(--c1) 60%, #000); stroke-width: 3; }
.bp-strap { fill: none; stroke: color-mix(in srgb, var(--c1) 60%, #000); stroke-width: 7; }
.bp-zip { fill: #fcc419; }

.seg { display: inline-flex; flex-wrap: wrap; align-items: center; gap: .25rem; }
.seg-l { font-size: .76rem; font-weight: 700; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); width: 100%; }
.seg button {
  border: 1px solid var(--line); background: var(--surface); border-radius: 8px;
  padding: .3rem .65rem; font-size: .88rem;
}
.seg button.on { background: var(--scene); border-color: var(--scene); color: #fff; font-weight: 650; }
.seg button:disabled { opacity: .5; }
.seg.focus { outline: 3px solid color-mix(in srgb, var(--scene) 45%, transparent); outline-offset: 4px; border-radius: 8px; }

.meter { display: grid; grid-template-columns: 6.2rem 1fr; align-items: center; gap: .5rem; font-size: .82rem; }
.meter-l { color: var(--muted); font-weight: 600; }
.bar { display: block; height: .6rem; background: var(--surface-2); border-radius: 999px; overflow: hidden; }
.bar i { display: block; height: 100%; width: var(--v, 0%); background: var(--scene); border-radius: inherit; transition: width .8s cubic-bezier(.2,.7,.2,1); }
.tag { font-size: .72rem; font-weight: 700; background: var(--surface-2); color: var(--muted); border-radius: 6px; padding: .05rem .4rem; vertical-align: middle; }
.tgl { display: flex; align-items: center; gap: .45rem; font-size: .88rem; cursor: pointer; }
.tgl input { width: 1.05rem; height: 1.05rem; accent-color: var(--scene); }
.shake { animation: shake .45s; }
@keyframes shake { 20%, 60% { transform: translateX(-6px); } 40%, 80% { transform: translateX(6px); } }

.pc { list-style: none; margin: .8rem 0 0; padding: 0; display: grid; gap: .4rem; font-size: .9rem; }
.pc li { padding: .45rem .65rem .45rem 2rem; border-radius: 8px; position: relative; background: var(--surface-2); }
.pc li::before { position: absolute; left: .65rem; top: .45rem; font-weight: 800; }
.pc .pro::before { content: "+"; color: var(--good); }
.pc .con::before { content: "−"; color: var(--bad); }
.pc .eg::before { content: "e.g."; font-size: .7rem; top: .6rem; left: .45rem; color: var(--muted); }
.ui-hint { margin: 0 0 .5rem; font-size: .9rem; color: var(--muted); }
/* ---------- pages ---------- */
.page h2 { font-size: 1.7rem; margin: .3rem 0 .6rem; }
.page h3 { font-size: 1.25rem; margin-bottom: .7rem; }
.lead { margin: 0 0 1rem; color: var(--muted); }
.dots3 { display: inline-flex; gap: 3px; margin-right: .4rem; vertical-align: middle; }
.dots3 i { width: .6rem; height: .6rem; border-radius: 50%; background: var(--surface-2); border: 1px solid var(--line); }
.dots3 i.on { background: var(--accent); border-color: var(--accent); }
.tbl.cmp td span { font-size: .84rem; }
.tbl.cmp td .dots3 { display: flex; margin-bottom: .2rem; }
.link-btn { border: 0; background: transparent; color: var(--c, var(--accent)); font-weight: 700; display: inline-flex; align-items: center; gap: .35rem; padding: 0; text-align: left; }
.link-btn:hover { text-decoration: underline; }
.scen { display: grid; grid-template-columns: repeat(auto-fill, minmax(18rem, 1fr)); gap: .8rem; }
.sc p { margin: 0 0 .6rem; }
.sc-btns { display: flex; flex-wrap: wrap; gap: .35rem; }
.sc-btns .right, .opt.right { background: color-mix(in srgb, var(--good) 18%, var(--surface)); border-color: var(--good); }
.sc-btns .wrong, .opt.wrong { background: color-mix(in srgb, var(--bad) 15%, var(--surface)); border-color: var(--bad); }
.sc-fb, .qz-fb { margin: .6rem 0 0; font-size: .9rem; color: var(--ink); }
.sc-fb.good, .qz-fb.good { border-left: 4px solid var(--good); padding-left: .6rem; }
.sc-fb.bad, .qz-fb.bad { border-left: 4px solid var(--bad); padding-left: .6rem; }
.terms-tools { display: flex; align-items: center; gap: 1rem; margin-bottom: 1rem; flex-wrap: wrap; }
.terms-tools input { border: 1px solid var(--line); background: var(--surface); border-radius: 10px; padding: .5rem .8rem; min-width: min(20rem, 100%); }
.terms { display: grid; grid-template-columns: repeat(auto-fill, minmax(15rem, 1fr)); gap: .7rem; }
.term { background: var(--surface); border: 1px solid var(--line); border-top: 4px solid var(--c); border-radius: var(--radius); padding: .8rem 1rem; box-shadow: var(--shadow); display: flex; flex-direction: column; gap: .35rem; }
.term h3 { font-size: 1.02rem; margin: 0; }
.term p { margin: 0; color: var(--muted); font-size: .92rem; flex: 1; }
.term .link-btn { font-size: .82rem; }
.term .link-btn .ic { width: 1rem; height: 1rem; }
.score { font-size: 1.05rem; margin: 0 0 1rem; }
.quiz { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(20rem, 1fr)); gap: .8rem; counter-reset: q; }
.qz { counter-increment: q; }
.qz-q { margin: 0 0 .6rem; font-weight: 650; }
.qz-q::before { content: counter(q) ". "; color: var(--accent); }
.qz-opts { display: grid; gap: .35rem; }
.opt { border: 1px solid var(--line); background: var(--surface); border-radius: 8px; padding: .45rem .7rem; text-align: left; }
.opt:hover { background: var(--surface-2); }
.qz.done .opt { pointer-events: none; }
.long { margin-bottom: .8rem; }
.long p { margin: 0 0 .5rem; }
.marks { color: var(--muted); font-weight: 650; white-space: nowrap; }
.long textarea { width: 100%; border: 1px solid var(--line); border-radius: 8px; background: var(--surface); padding: .6rem; margin-bottom: .5rem; resize: vertical; }
.scheme { margin: .6rem 0 0; padding-left: 1.2rem; display: grid; gap: .25rem; font-size: .92rem; }
#retry { margin-top: .4rem; }