:root {
  color-scheme: light;
  --primary: #087f97;
  --primary-strong: #075d70;
  --primary-soft: #dff7fb;
  --accent: #087f5b;
  --accent-soft: #dcfce7;
  --danger: #b42318;
  --danger-soft: #fee4e2;
  --warning: #a15c00;
  --warning-soft: #fff3d6;
  --advanced: #7a3eb1;
  --advanced-soft: #f1e8fb;
  --background: #f5fafb;
  --surface: #ffffff;
  --surface-raised: #ffffff;
  --surface-muted: #edf5f7;
  --text: #12313a;
  --text-muted: #526a72;
  --border: #c9dce1;
  --ring: #0e7490;
  --shadow: 0 18px 48px rgba(26, 71, 82, 0.10);
  --radius-lg: 20px;
  --radius-md: 12px;
  --max-width: 1240px;
}

[data-theme="dark"] {
  color-scheme: dark;
  --primary: #67e8f9;
  --primary-strong: #a5f3fc;
  --primary-soft: #153d46;
  --accent: #6ee7b7;
  --accent-soft: #123d32;
  --danger: #fda29b;
  --danger-soft: #4a2528;
  --warning: #facc6b;
  --warning-soft: #473719;
  --advanced: #d8b4fe;
  --advanced-soft: #3c2653;
  --background: #071a20;
  --surface: #0d252d;
  --surface-raised: #12313a;
  --surface-muted: #173943;
  --text: #ecfeff;
  --text-muted: #adc6cc;
  --border: #31525b;
  --ring: #67e8f9;
  --shadow: 0 18px 48px rgba(0, 0, 0, 0.28);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-width: 320px;
  min-height: 100vh;
  background: var(--background);
  color: var(--text);
  font: 400 16px/1.6 Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}
button, input { font: inherit; }
button { touch-action: manipulation; }
button, label { -webkit-tap-highlight-color: transparent; }
[data-page="landing"] .timer { visibility: hidden; }

.hidden { display: none !important; }
.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;
}
.skip-link {
  position: fixed; top: 8px; left: 8px; z-index: 1000; padding: 10px 14px;
  transform: translateY(-150%); background: var(--text); color: var(--surface); border-radius: 8px;
}
.skip-link:focus { transform: translateY(0); }

.app-header {
  display: flex; align-items: center; justify-content: space-between; gap: 24px;
  max-width: var(--max-width); margin: 0 auto; padding: 24px 28px;
}
.brand { display: flex; align-items: center; gap: 14px; }
.brand-mark {
  display: grid; place-items: center; width: 52px; height: 52px; border-radius: 14px;
  background: var(--primary); color: #fff; font-size: 14px; font-weight: 800; letter-spacing: .08em;
}
.brand h1 { margin: 0; font-size: 20px; line-height: 1.25; }
.eyebrow { margin: 0 0 3px; color: var(--primary-strong); font-size: 12px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.header-actions { display: flex; align-items: center; gap: 12px; }
.timer { display: flex; flex-direction: column; align-items: flex-end; line-height: 1.2; }
.timer-label { color: var(--text-muted); font-size: 12px; }
.timer strong { font-variant-numeric: tabular-nums; font-size: 18px; }
.icon-button {
  display: grid; place-items: center; width: 48px; height: 48px; padding: 0;
  border: 1px solid var(--border); border-radius: 50%; background: var(--surface); color: var(--text); cursor: pointer;
}
.icon-button svg, .review-button svg { width: 21px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }

.intro-shell { display: grid; place-items: center; min-height: calc(100vh - 108px); padding: 32px 24px 80px; }
.intro-card { width: min(720px, 100%); min-width: 0; padding: clamp(28px, 5vw, 56px); background: var(--surface); border: 1px solid var(--border); border-radius: 28px; box-shadow: var(--shadow); }
.intro-card h2 { margin: 8px 0 12px; font-size: clamp(34px, 6vw, 58px); line-height: 1.05; letter-spacing: -.035em; }
.intro-card > p:not(.eyebrow, .helper) { max-width: 60ch; color: var(--text-muted); font-size: 18px; }
.intro-metrics { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 12px; margin: 28px 0; }
.intro-metrics div { padding: 18px; background: var(--surface-muted); border-radius: var(--radius-md); text-align: center; }
.intro-metrics strong { display: block; font-size: 27px; line-height: 1.1; font-variant-numeric: tabular-nums; }
.intro-metrics span { color: var(--text-muted); font-size: 13px; }
.instructions { padding-left: 22px; color: var(--text-muted); }
.intro-actions, .results-actions, .dialog-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 30px; }
.helper { color: var(--text-muted); font-size: 14px; }

.button {
  min-height: 48px; padding: 11px 20px; border: 1px solid transparent; border-radius: 10px;
  font-weight: 750; cursor: pointer; transition: background-color 180ms ease, border-color 180ms ease, color 180ms ease, box-shadow 180ms ease;
}
.button.primary { background: var(--primary); color: #fff; }
[data-theme="dark"] .button.primary { color: #05242c; }
.button.primary:hover { background: var(--primary-strong); }
.button.secondary { background: var(--surface); border-color: var(--border); color: var(--text); }
.button.secondary:hover, .button.quiet:hover { background: var(--surface-muted); }
.button.success { background: var(--accent); color: #fff; }
[data-theme="dark"] .button.success { color: #062d23; }
.button.quiet { background: transparent; color: var(--text-muted); }
.button:disabled { opacity: .45; cursor: not-allowed; }
button:focus-visible, input:focus-visible + span { outline: 3px solid var(--ring); outline-offset: 3px; }

.assessment-shell { display: grid; grid-template-columns: 290px minmax(0, 780px); justify-content: center; gap: 32px; max-width: var(--max-width); margin: 0 auto; padding: 24px 28px 72px; }
.sidebar { position: sticky; top: 24px; align-self: start; padding: 24px; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-lg); }
.progress-copy { display: flex; justify-content: space-between; gap: 12px; color: var(--text-muted); font-size: 13px; font-weight: 700; }
.progress-track { height: 8px; margin: 12px 0 22px; overflow: hidden; background: var(--surface-muted); border-radius: 999px; }
.progress-track span { display: block; width: 0; height: 100%; background: var(--primary); transition: width 220ms ease; }
.question-nav { display: grid; grid-template-columns: repeat(5, 1fr); gap: 9px; }
.nav-button {
  display: grid; place-items: center; min-width: 44px; min-height: 44px; padding: 0;
  border: 1px solid var(--border); border-radius: 9px; background: var(--surface); color: var(--text-muted); font-weight: 750; cursor: pointer;
}
.nav-button.answered { background: var(--primary-soft); border-color: var(--primary); color: var(--primary-strong); }
.nav-button.review { box-shadow: inset 0 -4px 0 var(--warning); }
.nav-button.current { outline: 3px solid var(--ring); outline-offset: 2px; }
.nav-legend { display: grid; gap: 7px; margin-top: 22px; color: var(--text-muted); font-size: 12px; }
.nav-legend span { display: flex; align-items: center; gap: 8px; }
.nav-legend i { width: 13px; height: 13px; border-radius: 3px; }
.legend-current { outline: 2px solid var(--ring); }
.legend-answered { background: var(--primary-soft); border: 1px solid var(--primary); }
.legend-review { border-bottom: 4px solid var(--warning); }

.question-panel { min-height: 620px; padding: clamp(26px, 5vw, 52px); background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-lg); box-shadow: var(--shadow); }
.question-meta { display: flex; justify-content: space-between; align-items: center; gap: 16px; }
.question-badges { display: flex; flex-wrap: wrap; gap: 8px; }
.domain-badge, .difficulty-badge { display: inline-flex; align-items: center; min-height: 28px; padding: 4px 10px; border-radius: 999px; font-size: 12px; font-weight: 800; }
.domain-badge { background: var(--primary-soft); color: var(--primary-strong); }
.difficulty-basic { background: var(--accent-soft) !important; color: var(--accent) !important; }
.difficulty-intermediate { background: var(--warning-soft) !important; color: var(--warning) !important; }
.difficulty-advanced { background: var(--advanced-soft) !important; color: var(--advanced) !important; }
.review-button { display: inline-flex; align-items: center; gap: 7px; min-height: 44px; padding: 8px 10px; border: 0; background: transparent; color: var(--text-muted); cursor: pointer; }
.review-button[aria-pressed="true"] { color: var(--warning); font-weight: 750; }
.question-number { margin: 36px 0 5px; color: var(--text-muted); font-size: 13px; font-weight: 700; }
.question-title { max-width: 50ch; margin: 0; font-size: clamp(19px, 2.2vw, 24px); line-height: 1.5; letter-spacing: -.012em; }

/* ExamTopics prompts are longer, so keep their reading size compact. */
.compact-question-bank .question-title {
  max-width: 68ch;
  font-size: clamp(16px, 1.35vw, 17px);
  line-height: 1.58;
  letter-spacing: 0;
}

.compact-question-bank .answer-option {
  min-height: 50px;
  padding: 12px 15px;
  font-size: 14.5px;
  line-height: 1.5;
}
.selection-hint { margin: 10px 0 22px; color: var(--text-muted); font-size: 14px; }
.answer-options { display: grid; gap: 12px; margin: 0; padding: 0; border: 0; }
.answer-option { position: relative; display: flex; align-items: flex-start; gap: 13px; min-height: 56px; padding: 15px 17px; border: 1px solid var(--border); border-radius: var(--radius-md); cursor: pointer; transition: border-color 180ms ease, background-color 180ms ease; }
.answer-option:hover { border-color: var(--primary); background: var(--primary-soft); }
.answer-option.selected { border-color: var(--primary); background: var(--primary-soft); box-shadow: inset 3px 0 0 var(--primary); }
.answer-option input { position: absolute; opacity: 0; pointer-events: none; }
.option-key { flex: 0 0 28px; display: grid; place-items: center; width: 28px; height: 28px; margin-top: 1px; border: 1px solid var(--border); border-radius: 50%; color: var(--text-muted); font-size: 13px; font-weight: 800; }
.answer-option.selected .option-key { border-color: var(--primary); background: var(--primary); color: #fff; }
.option-copy { padding-top: 1px; }
.confidence-group { margin: 30px 0 0; padding: 0; border: 0; }
.confidence-group legend { margin-bottom: 10px; color: var(--text-muted); font-size: 13px; font-weight: 750; }
.confidence-options { display: flex; flex-wrap: wrap; gap: 9px; }
.confidence-options label { cursor: pointer; }
.confidence-options input { position: absolute; opacity: 0; }
.confidence-options span { display: grid; place-items: center; min-height: 44px; padding: 8px 15px; border: 1px solid var(--border); border-radius: 999px; color: var(--text-muted); font-size: 14px; }
.confidence-options input:checked + span { border-color: var(--primary); background: var(--primary-soft); color: var(--primary-strong); font-weight: 750; }
.inline-error { margin-top: 18px; padding: 10px 13px; background: var(--danger-soft); color: var(--danger); border-radius: 8px; }
.question-actions { display: flex; justify-content: space-between; gap: 12px; margin-top: 36px; }
.question-actions .primary, .question-actions .success { margin-left: auto; }

.results-shell { max-width: 1080px; margin: 0 auto; padding: 28px 28px 80px; }
.results-hero { display: grid; grid-template-columns: 160px minmax(0, 1fr); align-items: center; gap: 16px 34px; padding: clamp(28px, 5vw, 52px); background: var(--surface); border: 1px solid var(--border); border-radius: 24px; box-shadow: var(--shadow); }
.results-hero > .eyebrow { grid-column: 1 / -1; }
.score-ring { grid-row: 2 / 4; display: grid; place-items: center; align-content: center; width: 150px; height: 150px; border-radius: 50%; background: conic-gradient(var(--primary) 0%, var(--surface-muted) 0); box-shadow: inset 0 0 0 13px var(--surface); }
.score-ring strong { font-size: 34px; line-height: 1.1; font-variant-numeric: tabular-nums; }
.score-ring span { color: var(--text-muted); font-size: 13px; }
.results-heading h2 { margin: 0; font-size: clamp(28px, 4vw, 42px); line-height: 1.1; }
.results-heading p { max-width: 62ch; margin: 10px 0 0; color: var(--text-muted); }
.results-actions { margin: 0; }
.results-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; margin: 22px 0 48px; }
.metric-card { padding: 20px; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-md); }
.metric-card span { display: block; color: var(--text-muted); font-size: 13px; }
.metric-card strong { display: block; margin-top: 4px; font-size: 24px; font-variant-numeric: tabular-nums; }
.results-section { margin-top: 48px; }
.section-heading { display: flex; align-items: end; justify-content: space-between; gap: 24px; margin-bottom: 18px; }
.section-heading h2 { margin: 0; font-size: 28px; }
.section-heading > p { max-width: 44ch; margin: 0; color: var(--text-muted); font-size: 14px; text-align: right; }
.domain-results { display: grid; gap: 10px; }
.domain-row { display: grid; grid-template-columns: minmax(210px, 1fr) 3fr 70px; align-items: center; gap: 18px; padding: 17px 20px; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-md); }
.domain-row strong { font-size: 14px; }
.domain-bar { height: 10px; overflow: hidden; background: var(--surface-muted); border-radius: 999px; }
.domain-bar span { display: block; height: 100%; background: var(--primary); }
.domain-row.weak .domain-bar span { background: var(--warning); }
.domain-score { text-align: right; font-weight: 800; font-variant-numeric: tabular-nums; }
.filter-group { display: flex; gap: 6px; padding: 4px; background: var(--surface-muted); border-radius: 10px; }
.filter-button { min-height: 40px; padding: 6px 13px; border: 0; border-radius: 7px; background: transparent; color: var(--text-muted); cursor: pointer; }
.filter-button.active { background: var(--surface); color: var(--text); box-shadow: 0 2px 8px rgba(0,0,0,.08); }
.answer-review { display: grid; gap: 20px; }
.review-card { overflow: hidden; padding: 0; background: var(--surface); border: 1px solid var(--border); border-left: 5px solid var(--accent); border-radius: var(--radius-lg); }
.review-card.incorrect { border-left-color: var(--danger); }
.review-card-header { padding: 24px 26px 20px; }
.review-card h3 { max-width: 72ch; margin: 10px 0 16px; font-size: 19px; line-height: 1.5; }
.review-card p { margin: 7px 0; color: var(--text-muted); }
.review-card .answer-line { display: flex; flex-wrap: wrap; align-items: center; gap: 7px; }
.review-card .answer-line strong { color: var(--text); }
.review-tags { display: flex; flex-wrap: wrap; gap: 7px; }
.review-tags span { padding: 4px 8px; background: var(--surface-muted); border-radius: 999px; color: var(--text-muted); font-size: 12px; font-weight: 750; }
.review-card.incorrect .review-tags .status-tag { background: var(--danger-soft); color: var(--danger); }
.reason-panel { margin: 0 26px 24px; padding: 18px 20px; background: var(--primary-soft); border-radius: var(--radius-md); }
.reason-panel .reason-label { color: var(--primary-strong); font-size: 12px; font-weight: 850; letter-spacing: .08em; }
.reason-panel p { margin: 5px 0 0; color: var(--text); line-height: 1.7; }
.analysis-title { margin: 0; padding: 0 26px 10px; font-size: 14px; }
.option-analysis-list { display: grid; gap: 0; margin: 0; padding: 0; list-style: none; border-top: 1px solid var(--border); }
.option-analysis { padding: 18px 26px 19px; border-bottom: 1px solid var(--border); }
.option-analysis:last-child { border-bottom: 0; }
.option-analysis.is-correct { background: color-mix(in srgb, var(--accent-soft) 62%, var(--surface)); }
.option-analysis.is-selected:not(.is-correct) { background: color-mix(in srgb, var(--danger-soft) 52%, var(--surface)); }
.option-analysis-head { display: flex; flex-wrap: wrap; align-items: center; gap: 9px; }
.option-analysis-head > strong { flex: 1 1 320px; color: var(--text); line-height: 1.45; }
.analysis-key { flex: 0 0 30px; display: grid; place-items: center; width: 30px; height: 30px; border: 1px solid var(--border); border-radius: 50%; font-size: 13px; font-weight: 850; }
.is-correct .analysis-key { border-color: var(--accent); background: var(--accent); color: #fff; }
.is-selected:not(.is-correct) .analysis-key { border-color: var(--danger); background: var(--danger); color: #fff; }
.verdict, .selected-tag { padding: 3px 8px; border-radius: 999px; font-size: 12px; font-weight: 800; }
.verdict { background: var(--surface-muted); color: var(--text-muted); }
.is-correct .verdict { background: var(--accent-soft); color: var(--accent); }
.selected-tag { border: 1px solid currentColor; color: var(--danger); }
.is-correct .selected-tag { color: var(--accent); }
.option-analysis > p { margin: 9px 0 0 39px; line-height: 1.7; }

dialog { width: min(480px, calc(100% - 32px)); padding: 0; background: var(--surface); color: var(--text); border: 1px solid var(--border); border-radius: 18px; box-shadow: var(--shadow); }
dialog::backdrop { background: rgba(2, 20, 26, .58); }
dialog form { padding: 28px; }
dialog h2 { margin-top: 0; }
dialog p { color: var(--text-muted); }
.dialog-actions { justify-content: flex-end; }
.toast { position: fixed; right: 20px; bottom: 20px; z-index: 100; max-width: min(360px, calc(100% - 40px)); padding: 12px 16px; transform: translateY(140%); background: var(--text); color: var(--surface); border-radius: 9px; transition: transform 200ms ease; }
.toast.show { transform: translateY(0); }

@media (max-width: 900px) {
  .assessment-shell { grid-template-columns: 1fr; }
  .sidebar { position: static; }
  .question-nav { grid-template-columns: repeat(10, 1fr); }
  .nav-legend { grid-template-columns: repeat(3, 1fr); }
  .results-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 620px) {
  .app-header { padding: 16px; }
  .brand { min-width: 0; }
  .brand-mark { width: 44px; height: 44px; border-radius: 11px; }
  .brand .eyebrow { display: none; }
  .brand h1 { overflow: hidden; font-size: 16px; white-space: nowrap; text-overflow: ellipsis; }
  .timer-label { display: none; }
  .intro-shell, .assessment-shell, .results-shell { padding-left: 14px; padding-right: 14px; }
  .intro-card, .question-panel { padding: 24px 18px; border-radius: 18px; }
  .compact-question-bank .question-title { font-size: 16px; line-height: 1.55; }
  .compact-question-bank .answer-option { padding: 11px 13px; font-size: 14px; }
  .intro-card h2 { overflow-wrap: anywhere; font-size: clamp(32px, 11vw, 44px); }
  .intro-metrics { gap: 8px; }
  .intro-metrics div { padding: 14px 7px; }
  .question-nav { grid-template-columns: repeat(5, minmax(44px, 1fr)); }
  .question-meta { align-items: flex-start; }
  .review-button { max-width: 130px; text-align: left; }
  .question-actions { position: sticky; bottom: 0; margin: 30px -18px -24px; padding: 12px 18px calc(12px + env(safe-area-inset-bottom)); background: color-mix(in srgb, var(--surface) 94%, transparent); border-top: 1px solid var(--border); backdrop-filter: blur(8px); }
  .results-hero { display: flex; flex-direction: column; align-items: flex-start; }
  .score-ring { align-self: center; }
  .results-actions { width: 100%; }
  .results-actions .button { width: 100%; }
  .results-grid { grid-template-columns: 1fr 1fr; }
  .section-heading { align-items: flex-start; flex-direction: column; }
  .section-heading > p { text-align: left; }
  .domain-row { grid-template-columns: 1fr 60px; gap: 9px 12px; }
  .domain-bar { grid-column: 1 / -1; grid-row: 2; }
  .domain-score { grid-column: 2; grid-row: 1; }
  .filter-group { width: 100%; }
  .filter-button { flex: 1; }
  .review-card-header { padding: 20px 18px 16px; }
  .reason-panel { margin: 0 18px 20px; padding: 16px; }
  .analysis-title { padding: 0 18px 9px; }
  .option-analysis { padding: 16px 18px; }
  .option-analysis-head > strong { flex-basis: calc(100% - 42px); }
  .option-analysis > p { margin-left: 0; }
}

@media (max-width: 390px) {
  .header-actions .timer { display: none; }
  .intro-metrics span { font-size: 11px; }
  .results-grid { grid-template-columns: 1fr; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; animation-duration: .01ms !important; }
}