:root {
  --bg: #f4f6fb;
  --fg: #1b2433;
  --card: #ffffff;
  --muted: #667085;
  --muted-bg: #f3f4f6;
  --border: #e4e7ee;
  --primary: #153e90;
  --primary-soft: rgba(21, 62, 144, 0.08);
  --primary-ring: rgba(21, 62, 144, 0.28);
  --primary-fg: #ffffff;
  --success: #6ee75a;
  --success-fg: #143018;
  --danger: #d92d20;
  --danger-soft: rgba(217, 45, 32, 0.1);
  --shadow: 0 1px 2px rgba(16, 24, 40, 0.06);
  --radius: 12px;
  --max: 48rem;
  --narrow: 42rem;
  font-family: "Segoe UI", ui-sans-serif, system-ui, sans-serif;
  color: var(--fg);
  background: var(--bg);
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }

html, body { margin: 0; min-height: 100%; }

body {
  background: var(--bg);
  color: var(--fg);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

body.exam-lock {
  user-select: none;
  -webkit-user-select: none;
}

img, svg { display: block; }

a { color: inherit; }

button, input, select { font: inherit; }

.page {
  min-height: 100vh;
  padding: 2.5rem 1rem;
}

.page-exam { padding: 1.5rem 1rem; }

.wrap { width: 100%; max-width: var(--max); margin: 0 auto; }
.wrap-narrow { max-width: var(--narrow); }

.center { text-align: center; }

.hero { display: flex; flex-direction: column; align-items: center; }

.badge-icon,
.rule-icon,
.stat-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary);
  background: var(--primary-soft);
}

.badge-icon {
  width: 3.5rem;
  height: 3.5rem;
  margin-bottom: 1rem;
  border-radius: 1rem;
  background: var(--primary);
  color: var(--primary-fg);
}

.badge-icon .icon { width: 1.75rem; height: 1.75rem; }
.badge-icon.sm { width: 3rem; height: 3rem; margin-bottom: 0.75rem; border-radius: 0.75rem; }
.badge-icon.sm .icon { width: 1.5rem; height: 1.5rem; }

h1, h2, p { margin: 0; }

h1 {
  font-size: 1.875rem;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

h2 { font-size: 0.95rem; }

.lede {
  margin-top: 0.75rem;
  max-width: 36rem;
  color: var(--muted);
}

.muted { color: var(--muted); }
.small { font-size: 0.875rem; }
.tiny { font-size: 0.75rem; }
.strong { font-weight: 650; color: var(--fg); }

.grid-3, .grid-2 { display: grid; gap: 1rem; }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); margin-top: 2.5rem; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.card-pad { padding: 1.5rem; }
.feature { padding: 1.25rem; }
.feature .badge-icon,
.mini-icon {
  width: 2.5rem;
  height: 2.5rem;
  margin-bottom: 0;
  border-radius: 0.6rem;
  background: var(--primary-soft);
  color: var(--primary);
}

.mini-icon { display: flex; align-items: center; justify-content: center; }
.mini-icon .icon, .feature .icon { width: 1.25rem; height: 1.25rem; }

.section-title { margin-top: 2rem; }
.course-list { margin-top: 1rem; }

.course p + p, .feature p { margin-top: 0.35rem; }

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  border: 0;
  border-radius: 0.5rem;
  padding: 0.75rem 1.5rem;
  background: var(--primary);
  color: var(--primary-fg);
  font-size: 0.875rem;
  font-weight: 650;
  text-decoration: none;
  cursor: pointer;
  transition: opacity 0.15s ease;
}

.btn:hover { opacity: 0.92; }
.btn:focus-visible { outline: 2px solid var(--primary); outline-offset: 2px; }
.btn .icon { width: 1rem; height: 1rem; }
.btn-block { width: 100%; margin-top: 1.5rem; }
.btn:disabled { cursor: not-allowed; opacity: 0.5; }

.stack { display: flex; flex-direction: column; gap: 1rem; }
.field { display: flex; flex-direction: column; gap: 0.4rem; }
.label { font-size: 0.875rem; font-weight: 600; }

.input, .select {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  background: var(--card);
  color: var(--fg);
  padding: 0.65rem 0.75rem;
  outline: none;
}

.input:focus, .select:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-ring);
}

.choice, .option {
  display: flex;
  width: 100%;
  text-align: left;
  border: 2px solid var(--border);
  border-radius: 0.65rem;
  background: var(--card);
  cursor: pointer;
  transition: border-color 0.15s ease, background 0.15s ease;
}

.choice { flex-direction: column; gap: 0.25rem; padding: 1rem; }
.choice:hover, .option:hover { border-color: rgba(21, 62, 144, 0.4); }

.choice, .option, .agree { position: relative; }

.choice input, .option input, .agree input {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  margin: 0;
  opacity: 0;
  cursor: pointer;
}

.choice-top, .option {
  align-items: center;
}

.choice-top { display: flex; justify-content: space-between; gap: 0.75rem; }

.mark, .tick {
  display: flex;
  align-items: center;
  justify-content: center;
  flex: none;
  border: 2px solid rgba(102, 112, 133, 0.45);
  color: transparent;
}

.mark {
  width: 1.25rem;
  height: 1.25rem;
  border-radius: 999px;
}

.mark .icon, .tick .icon { width: 0.8rem; height: 0.8rem; }

.choice:has(input:checked),
.option:has(input:checked) {
  border-color: var(--primary);
  background: var(--primary-soft);
  box-shadow: 0 0 0 3px rgba(21, 62, 144, 0.12);
}

.choice:has(input:checked) .mark,
.agree:has(input:checked) .tick {
  border-color: var(--primary);
  background: var(--primary);
  color: var(--primary-fg);
}

.option { gap: 0.75rem; padding: 1rem; }
.letter {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2rem;
  height: 2rem;
  flex: none;
  border-radius: 0.45rem;
  background: var(--muted-bg);
  color: var(--muted);
  font-size: 0.875rem;
  font-weight: 700;
}

.option:has(input:checked) .letter {
  background: var(--primary);
  color: var(--primary-fg);
}

.alert {
  margin-top: 1.5rem;
  border: 1px solid rgba(217, 45, 32, 0.4);
  border-radius: 0.65rem;
  background: var(--danger-soft);
  color: var(--danger);
  padding: 1rem;
  font-size: 0.875rem;
}

.alert ul { margin: 0; padding-left: 1.1rem; }
.alert li + li { margin-top: 0.25rem; }
.alert p + p { margin-top: 0.2rem; }

.pill {
  display: inline-flex;
  align-items: center;
  border-radius: 999px;
  background: var(--primary-soft);
  color: var(--primary);
  padding: 0.25rem 0.75rem;
  font-size: 0.75rem;
  font-weight: 700;
}

.rules { display: flex; flex-direction: column; gap: 0.75rem; margin-top: 1.5rem; list-style: none; padding: 0; }
.rule {
  display: flex;
  gap: 0.75rem;
  border: 1px solid var(--border);
  border-radius: 0.65rem;
  background: var(--bg);
  padding: 1rem;
}

.rule-icon {
  width: 2.25rem;
  height: 2.25rem;
  flex: none;
  border-radius: 0.55rem;
}

.rule-icon .icon { width: 1.2rem; height: 1.2rem; }

.agree {
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
  margin-top: 1.5rem;
  border: 1px solid var(--border);
  border-radius: 0.65rem;
  background: var(--bg);
  padding: 1rem;
  cursor: pointer;
}

.tick {
  width: 1.25rem;
  height: 1.25rem;
  margin-top: 0.1rem;
  border-radius: 0.25rem;
}

.topbar {
  display: flex;
  justify-content: space-between;
  gap: 0.75rem;
  align-items: center;
  padding: 1rem;
}

.kicker {
  font-size: 0.75rem;
  font-weight: 650;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--muted);
}

.timers { display: flex; gap: 0.75rem; flex-wrap: wrap; }
.timer {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  border-radius: 0.45rem;
  background: var(--bg);
  padding: 0.4rem 0.75rem;
  font-variant-numeric: tabular-nums;
  font-weight: 700;
  font-size: 0.875rem;
}

.timer .icon { width: 1rem; height: 1rem; color: var(--primary); }
.timer.is-danger { background: var(--danger-soft); color: var(--danger); }
.timer.is-danger .icon { color: var(--danger); }

.progress {
  height: 0.5rem;
  margin-top: 0.75rem;
  overflow: hidden;
  border-radius: 999px;
  background: #e7e9ee;
}

.progress > span {
  display: block;
  height: 100%;
  border-radius: inherit;
  background: var(--primary);
}

.question { margin-top: 1rem; }
.question h1 { font-size: 1.125rem; letter-spacing: 0; font-weight: 650; }
.options { display: flex; flex-direction: column; gap: 0.75rem; margin-top: 1.25rem; }

.exam-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 1rem;
}

.exam-shell {
  width: min(1120px, 100%);
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(0, 1fr) 300px;
  gap: 1rem;
  align-items: start;
}

.palette {
  padding: 1rem;
  position: sticky;
  top: 1rem;
  max-height: calc(100vh - 2rem);
  overflow: auto;
}
.palette-head { display: flex; align-items: center; gap: 0.75rem; }
.palette-head img { width: 28px; height: 28px; }

.palette-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem;
  margin-top: 1rem;
}

.palette-stats div {
  border-radius: 0.55rem;
  background: var(--bg);
  padding: 0.65rem 0.5rem;
  text-align: center;
}

.palette-stats strong {
  display: block;
  font-size: 1.35rem;
  font-variant-numeric: tabular-nums;
  line-height: 1.1;
}

.palette-stats span {
  display: block;
  margin-top: 0.15rem;
  font-size: 0.7rem;
  color: var(--muted);
}

.palette-stats div:first-child strong { color: var(--primary); }
.palette-stats div:last-child strong { color: #98a2b3; }

.pixel-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem 0.75rem;
  margin: 0.85rem 0 0.75rem;
  padding: 0;
  list-style: none;
  font-size: 0.7rem;
  color: var(--muted);
}

.pixel-legend li { display: flex; align-items: center; gap: 0.35rem; }

.pixel-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
}

.pixel {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  grid-template-rows: repeat(5, 1fr);
  gap: 1px;
  aspect-ratio: 1;
  background: transparent;
}

.px-top,
.px-body,
.px-foot {
  background: transparent;
  border: 1px solid #e1e5ee;
}

.px-top { grid-column: 5; grid-row: 1; }
.px-body {
  grid-column: 2 / span 3;
  grid-row: 2 / span 3;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #98a2b3;
  font-size: 0.72rem;
  font-style: normal;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}
.px-foot { grid-column: 1; grid-row: 5; }

.pixel.is-marked .px-top {
  border-color: #54e346;
  background: #54e346;
}

.pixel.is-marked .px-body,
.pixel.is-marked .px-foot {
  border-color: #153e90;
  background: #153e90;
  color: #fff;
}

.pixel.is-current:not(.is-marked) .px-body {
  border-color: #153e90;
  color: #153e90;
  box-shadow: inset 0 0 0 1px #153e90;
}

.pixel.is-sample {
  width: 1.4rem;
  height: 1.4rem;
  flex: none;
}

.pixel.is-sample .px-body { font-size: 0; border-width: 1px; }

.linkish {
  border: 0;
  background: none;
  color: inherit;
  font-weight: 700;
  text-decoration: underline;
  text-underline-offset: 2px;
  cursor: pointer;
  padding: 0;
}

.result-hero {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.75rem;
  background: var(--primary);
  color: var(--primary-fg);
  text-align: center;
  padding: 2rem 1.5rem;
}

.result-hero .icon { width: 2.5rem; height: 2.5rem; }
.score { font-size: 2.25rem; font-weight: 800; font-variant-numeric: tabular-nums; }
.score span { font-size: 1.25rem; font-weight: 650; opacity: 0.8; }
.result-rank { margin: 0; font-weight: 700; font-variant-numeric: tabular-nums; }
.rank-note { padding: 0.85rem 1rem 0; }
.review-time { margin-top: 0.35rem; }

.verdict {
  display: inline-flex;
  border-radius: 999px;
  padding: 0.35rem 1rem;
  font-size: 0.875rem;
  font-weight: 800;
}

.verdict.pass { background: var(--success); color: var(--success-fg); }
.verdict.fail { background: var(--danger); color: #fff; }

.meta {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1px;
  background: var(--border);
}

.meta > div { background: var(--card); padding: 1rem; }
.meta p + p { margin-top: 0.25rem; overflow-wrap: anywhere; }

.stats { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 0.75rem; margin-top: 1rem; }
.stat { display: flex; flex-direction: column; align-items: center; gap: 0.25rem; padding: 1rem; text-align: center; }
.stat .icon { width: 1.25rem; height: 1.25rem; }
.stat strong { font-size: 1.5rem; font-variant-numeric: tabular-nums; }
.tone-primary { color: var(--primary); }
.tone-danger { color: var(--danger); }
.tone-muted { color: var(--muted); }

.reviews { display: flex; flex-direction: column; gap: 0.75rem; margin-top: 0.75rem; }
.review { border-left-width: 4px; padding: 1rem; }
.review.correct { border-left-color: var(--primary); }
.review.wrong { border-left-color: var(--danger); }
.review.unanswered { border-left-color: #98a2b3; }

.review-top { display: flex; justify-content: space-between; gap: 0.75rem; align-items: flex-start; }
.status { display: inline-flex; align-items: center; gap: 0.25rem; flex: none; font-size: 0.75rem; font-weight: 700; }
.status .icon { width: 1rem; height: 1rem; }

.answer-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0.5rem; margin-top: 0.75rem; }
.answer-box { border-radius: 0.45rem; background: var(--bg); padding: 0.65rem; }

.footnote { margin-top: 2rem; text-align: center; }

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

@media (max-width: 960px) {
  .exam-shell { grid-template-columns: 1fr; }
  .palette { position: static; }
}

@media (max-width: 720px) {
  h1 { font-size: 1.6rem; }
  .grid-3, .grid-2, .meta, .answer-grid { grid-template-columns: 1fr; }
  .topbar, .exam-footer { flex-direction: column; align-items: stretch; }
  .stats { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}