:root {
  --bg: #f6f3ec;
  --surface: #ffffff;
  --surface-2: #efebe2;
  --ink: #1d1c1a;
  --muted: #5b5750;
  --line: #d9d3c6;
  --focus: #1f5fbf;

  --divide: #1f5fbf;
  --multiply: #7a3fc9;
  --subtract: #c2410c;
  --bringdown: #0f766e;
  --beat-ink: #ffffff;

  --lost-bg: #fde68a;
  --lost-ink: #5c3b00;
  --lost-edge: #e9b949;
  --good: #166534;
  --good-bg: #dcfce7;
  --warn: #7c2d12;
  --warn-bg: #ffedd5;
  --highlight: #ffe98a;

  --radius: 18px;
  --shadow: 0 1px 2px rgb(0 0 0 / 0.06), 0 8px 24px rgb(0 0 0 / 0.06);
  --font: 'Atkinson Hyperlegible', system-ui, -apple-system, 'Segoe UI', Arial, sans-serif;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme='light']) {
    --bg: #16171a;
    --surface: #212328;
    --surface-2: #2a2d33;
    --ink: #f2efe8;
    --muted: #aaa59b;
    --line: #3a3d44;
    --focus: #8fb4ff;
    --divide: #6f9dff;
    --multiply: #b18cff;
    --subtract: #ff8f5a;
    --bringdown: #3cc4b4;
    --beat-ink: #111214;
    --lost-bg: #4a3b10;
    --lost-ink: #ffe7a3;
    --lost-edge: #8a6d1d;
    --good: #86efac;
    --good-bg: #173524;
    --warn: #fdba74;
    --warn-bg: #3d2413;
    --highlight: #6b5a12;
    --shadow: 0 1px 2px rgb(0 0 0 / 0.4);
    color-scheme: dark;
  }
}

:root[data-theme='dark'] {
  --bg: #16171a;
  --surface: #212328;
  --surface-2: #2a2d33;
  --ink: #f2efe8;
  --muted: #aaa59b;
  --line: #3a3d44;
  --focus: #8fb4ff;
  --divide: #6f9dff;
  --multiply: #b18cff;
  --subtract: #ff8f5a;
  --bringdown: #3cc4b4;
  --beat-ink: #111214;
  --lost-bg: #4a3b10;
  --lost-ink: #ffe7a3;
  --lost-edge: #8a6d1d;
  --good: #86efac;
  --good-bg: #173524;
  --warn: #fdba74;
  --warn-bg: #3d2413;
  --highlight: #6b5a12;
  --shadow: 0 1px 2px rgb(0 0 0 / 0.4);
  color-scheme: dark;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font);
  font-size: 1.15rem;
  line-height: 1.5;
  letter-spacing: 0.01em;
}

[hidden] { display: none !important; }

h1, h2, h3 { line-height: 1.2; margin: 0 0 0.5em; }
h1 { font-size: clamp(1.8rem, 3vw + 1rem, 2.8rem); }
h2 { font-size: 1.35rem; }

:focus-visible { outline: 3px solid var(--focus); outline-offset: 3px; border-radius: 6px; }

.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

/* ---------- Top bar ---------- */

.topbar {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 12px 24px;
  background: var(--surface);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 5;
}
.brand {
  display: flex; align-items: center; gap: 10px;
  color: var(--ink); text-decoration: none; font-weight: 700; font-size: 1.2rem;
}
.brand-mark {
  display: grid; place-items: center;
  width: 36px; height: 36px; border-radius: 10px;
  background: var(--divide); color: var(--beat-ink); font-size: 1.5rem;
}
.topbar-problem {
  flex: 1;
  text-align: center;
  font-size: 1.6rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.notice {
  margin: 0; padding: 10px 24px;
  background: var(--warn-bg); color: var(--warn); text-align: center;
}

main { max-width: 1180px; margin: 0 auto; padding: 28px 24px 64px; }

/* ---------- Buttons ---------- */

.btn {
  font: inherit;
  font-weight: 700;
  min-height: 52px;
  padding: 10px 20px;
  border-radius: 14px;
  border: 2px solid var(--line);
  background: var(--surface);
  color: var(--ink);
  cursor: pointer;
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  transition: transform 80ms ease, background-color 120ms ease;
}
.btn:hover { background: var(--surface-2); }
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: 0.45; cursor: default; }
.btn.primary { background: var(--ink); border-color: var(--ink); color: var(--bg); }
.btn.primary:hover { filter: brightness(1.15); }
.btn.lost { background: var(--lost-bg); border-color: var(--lost-edge); color: var(--lost-ink); }
.btn.lost:hover { filter: brightness(0.97); }
.btn.ghost { border-color: transparent; background: transparent; }
.btn.big { min-height: 64px; font-size: 1.2rem; padding: 12px 26px; }
.btn.wide { width: 100%; }
.btn svg { width: 22px; height: 22px; flex: none; }

.link-btn {
  font: inherit; font-weight: 700; color: var(--focus);
  background: none; border: none; padding: 6px 0; cursor: pointer;
  text-decoration: underline; text-underline-offset: 3px;
}

/* ---------- Cards and home ---------- */

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 28px;
  margin-bottom: 24px;
}

.home { max-width: 760px; margin: 0 auto; }
.home-intro { margin: 8px 0 28px; }
.lede { font-size: 1.3rem; color: var(--muted); margin: 0; max-width: 36ch; }

.entry-row { display: flex; align-items: flex-end; gap: 16px; flex-wrap: wrap; }
.entry-field { display: grid; gap: 6px; font-weight: 700; color: var(--muted); font-size: 1rem; }
.entry-field input {
  font: inherit;
  font-size: 2.6rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.12em;
  width: 7.2ch;
  padding: 6px 14px;
  border-radius: 14px;
  border: 2px solid var(--line);
  background: var(--bg);
  color: var(--ink);
}
.entry-field.small input { width: 3.6ch; }
.entry-field input:focus { border-color: var(--focus); outline: none; box-shadow: 0 0 0 3px color-mix(in srgb, var(--focus) 30%, transparent); }
.entry-op { font-size: 2.6rem; font-weight: 700; padding-bottom: 8px; }
.entry-error { color: var(--warn); font-weight: 700; min-height: 1.5em; margin: 10px 0; }
.entry-actions { display: flex; gap: 12px; flex-wrap: wrap; }
.examples { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-top: 22px; color: var(--muted); }

.chips { display: flex; gap: 10px; flex-wrap: wrap; }
.chip {
  font: inherit; font-weight: 700; font-size: 1.2rem;
  font-variant-numeric: tabular-nums;
  padding: 8px 18px; min-height: 48px;
  border-radius: 999px; border: 2px solid var(--line);
  background: var(--bg); color: var(--ink); cursor: pointer;
}
.chip:hover { border-color: var(--ink); }
.chip.done { border-color: var(--good); }
.chip.done::after { content: ' ✓'; color: var(--good); }

.teacher summary { cursor: pointer; font-weight: 700; font-size: 1.15rem; }
.teacher p { color: var(--muted); }
.teacher textarea, .link-out input {
  font: inherit; width: 100%; padding: 12px 14px;
  border-radius: 12px; border: 2px solid var(--line);
  background: var(--bg); color: var(--ink);
}
.link-out { display: flex; gap: 10px; margin-top: 14px; }
.link-out input { font-size: 0.95rem; }

/* ---------- Coach ---------- */

.coach {
  display: grid;
  grid-template-columns: minmax(280px, 360px) 1fr;
  gap: 28px;
  align-items: start;
}
.coach-side { display: grid; gap: 20px; position: sticky; top: 92px; }
.coach-main { display: grid; gap: 16px; }

.ring svg { width: 100%; height: auto; display: block; }
.ring .track { fill: none; stroke: var(--line); stroke-width: 6; }
.ring .arrow { fill: var(--line); }
.ring .node circle { fill: var(--surface); stroke: var(--line); stroke-width: 3; transition: fill 200ms, stroke 200ms; }
.ring .node text { fill: var(--muted); font-family: var(--font); font-weight: 700; text-anchor: middle; }
.ring .node .sym { font-size: 30px; }
.ring .node .lbl { font-size: 12.5px; }
.ring .node.active circle { fill: var(--beat); stroke: var(--beat); }
.ring .node.active text { fill: var(--beat-ink); }
.ring .node.past circle { stroke: var(--beat); }
.ring .center-small { fill: var(--muted); font: 700 15px var(--font); text-anchor: middle; }
.ring .center-big { fill: var(--ink); font: 700 30px var(--font); text-anchor: middle; }

.diagram {
  margin: 0;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px 16px 10px;
}
.diagram svg { width: 100%; height: auto; display: block; max-height: 260px; }
.diagram figcaption { color: var(--muted); font-size: 0.95rem; text-align: center; margin-top: 6px; }
.diagram .digit { font: 700 34px var(--font); fill: var(--ink); text-anchor: middle; }
.diagram .digit.dim { fill: var(--muted); opacity: 0.55; }
.diagram .bar { stroke: var(--ink); stroke-width: 3; fill: none; stroke-linecap: round; }
.diagram .qbox { fill: none; stroke: var(--line); stroke-width: 2.5; stroke-dasharray: 6 5; }
.diagram .qbox.filled { fill: var(--surface-2); stroke: var(--muted); stroke-dasharray: none; }
.diagram .qcheck { font: 700 22px var(--font); fill: var(--muted); text-anchor: middle; }
.diagram .qbox.hot { stroke: var(--beat); fill: color-mix(in srgb, var(--beat) 16%, transparent); stroke-dasharray: none; stroke-width: 3.5; }
.diagram .hot-digit { fill: color-mix(in srgb, var(--beat) 20%, transparent); }
.diagram .hot-line { stroke: var(--beat); stroke-width: 4; stroke-linecap: round; }
.diagram .hot-text { font: 700 14px var(--font); fill: var(--beat); text-anchor: middle; }
.diagram .pulse { animation: pulse 1.6s ease-in-out infinite; }
@keyframes pulse { 50% { opacity: 0.45; } }

.step-card {
  --beat: var(--ink);
  background: var(--surface);
  border: 1px solid var(--line);
  border-top: 10px solid var(--beat);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px 30px 28px;
  min-height: 360px;
}
.step-head { display: flex; align-items: center; gap: 14px; margin-bottom: 18px; }
.step-symbol {
  display: grid; place-items: center;
  width: 52px; height: 52px; border-radius: 14px;
  background: var(--beat); color: var(--beat-ink);
  font-size: 2rem; font-weight: 700; flex: none;
}
.step-name { margin: 0; font-size: 1.7rem; font-weight: 700; color: var(--beat); }
.step-round { margin-left: auto; color: var(--muted); font-weight: 700; }

.block { display: flex; gap: 12px; align-items: flex-start; margin: 0 0 16px; }
.speak {
  flex: none;
  width: 44px; height: 44px; margin-top: 2px;
  border-radius: 12px; border: 2px solid var(--line);
  background: var(--surface); color: var(--muted);
  display: grid; place-items: center; cursor: pointer;
}
.speak:hover { color: var(--ink); border-color: var(--ink); }
.speak svg { width: 22px; height: 22px; }

.say { margin: 0; }
.say .w { border-radius: 6px; padding: 0 1px; transition: background-color 90ms; box-decoration-break: clone; -webkit-box-decoration-break: clone; }
.say .w.on { background: var(--highlight); }
.say .num { font-weight: 700; font-variant-numeric: tabular-nums; }

.block.question .say { font-size: clamp(1.7rem, 1.2rem + 1.6vw, 2.5rem); font-weight: 700; line-height: 1.3; }
.block.context .say { font-size: 1.3rem; }
.block.where .say { font-size: 1.3rem; }
.block.where { padding: 14px 16px; border-radius: 14px; background: var(--surface-2); }
.block.selfcheck { padding: 14px 16px; border-radius: 14px; border: 2px dashed var(--beat); }
.block.selfcheck .say { font-size: 1.2rem; font-weight: 700; }
.block.tip { padding: 14px 16px; border-radius: 14px; background: color-mix(in srgb, var(--beat) 10%, var(--surface)); }
.block.feedback.good { padding: 12px 16px; border-radius: 14px; background: var(--good-bg); color: var(--good); font-weight: 700; }
.block.feedback.bad { padding: 12px 16px; border-radius: 14px; background: var(--warn-bg); color: var(--warn); font-weight: 700; }

.check { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; margin: 20px 0 8px; padding-top: 18px; border-top: 1px solid var(--line); }
.check label { font-weight: 700; color: var(--muted); }
.check input {
  font: inherit; font-size: 1.5rem; font-weight: 700; font-variant-numeric: tabular-nums;
  width: 5.5ch; padding: 4px 12px; border-radius: 12px;
  border: 2px solid var(--line); background: var(--bg); color: var(--ink);
}
.check .btn { min-height: 48px; }
.optional { font-weight: 400; color: var(--muted); }

.coach-nav { display: grid; grid-template-columns: auto auto 1fr; gap: 12px; }
.coach-nav .btn { white-space: nowrap; }
.coach-nav .btn.primary { font-size: 1.2rem; }

/* ---------- Ladder ---------- */

.ladder { max-width: 860px; margin: 0 auto; }
.ladder-card { padding: 30px 32px; }
.ladder-card .kicker { color: var(--muted); font-weight: 700; margin: 0 0 12px; text-transform: uppercase; letter-spacing: 0.08em; font-size: 0.9rem; }
.ladder-card .block.question .say { font-size: clamp(1.5rem, 1.1rem + 1.4vw, 2.1rem); }
.count-options { display: flex; gap: 12px; flex-wrap: wrap; margin: 10px 0 20px; }
.count-options .btn { min-width: 96px; min-height: 80px; font-size: 1.6rem; }
.mark-options { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; margin: 10px 0 20px; }
.mark-option {
  font: inherit; text-align: left; cursor: pointer;
  display: grid; grid-template-columns: 120px 1fr; gap: 14px; align-items: center;
  padding: 14px; border-radius: 16px; border: 2px solid var(--line);
  background: var(--bg); color: var(--ink); font-weight: 700; font-size: 1.1rem;
}
.mark-option:hover { border-color: var(--ink); }
.mark-option svg { width: 120px; height: 90px; }
.sketch .box { fill: var(--surface-2); stroke: var(--muted); stroke-width: 2; }
.sketch .bar { stroke: var(--ink); stroke-width: 3; fill: none; stroke-linecap: round; }
.sketch .hot { fill: var(--lost-bg); stroke: var(--lost-ink); stroke-width: 3; }
.sketch .hot-line { stroke: var(--lost-ink); stroke-width: 4; stroke-linecap: round; }
.ladder-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 8px; }

/* ---------- Settings ---------- */

dialog {
  border: 1px solid var(--line); border-radius: var(--radius);
  background: var(--surface); color: var(--ink);
  padding: 28px; width: min(520px, calc(100vw - 32px));
  box-shadow: 0 20px 60px rgb(0 0 0 / 0.25);
}
dialog::backdrop { background: rgb(0 0 0 / 0.35); }
.settings-form { display: grid; gap: 18px; }
.settings-form fieldset { border: none; padding: 0; margin: 0; display: flex; gap: 16px; flex-wrap: wrap; }
.settings-form legend { font-weight: 700; margin-bottom: 8px; }
.settings-form label { display: flex; align-items: center; gap: 8px; }
.settings-form input[type='radio'], .settings-form input[type='checkbox'] { width: 22px; height: 22px; }
.settings-form .select { display: grid; gap: 6px; font-weight: 700; }
.settings-form select { font: inherit; padding: 10px; border-radius: 12px; border: 2px solid var(--line); background: var(--bg); color: var(--ink); }
.settings-actions { display: flex; justify-content: flex-end; }

/* ---------- Small screens ---------- */

@media (max-width: 900px) {
  .coach { grid-template-columns: 1fr; }
  .coach-main { order: -1; }
  .coach-side { position: static; grid-template-columns: 1fr 1fr; align-items: center; }
  .ring { max-width: 300px; margin: 0 auto; width: 100%; }
}

@media (max-width: 640px) {
  main { padding: 20px 16px 48px; }
  .topbar { padding: 10px 16px; gap: 10px; }
  .brand span:last-child { display: none; }
  .topbar-problem { font-size: 1.3rem; }
  .card, .ladder-card { padding: 20px; }
  .step-card { padding: 18px 18px 22px; }
  .coach-side { grid-template-columns: 1fr; }
  .ring { max-width: 240px; }
  .coach-nav { grid-template-columns: 1fr 1fr; }
  .coach-nav .btn.primary { grid-column: 1 / -1; grid-row: 1; }
  .mark-options { grid-template-columns: 1fr; }
  .entry-actions .btn { width: 100%; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; animation: none !important; }
}