:root {
  --bg: #07111f;
  --bg2: #132238;
  --panel: rgba(8, 15, 27, 0.84);
  --text: #f8fafc;
  --muted: #cbd5e1;
  --line: rgba(255,255,255,.1);
  --accent: #22c55e;
  --accent2: #38bdf8;
  --accent3: #8b5cf6;
  --danger: #ef4444;
  --radius: 28px;
  --shadow: 0 24px 60px rgba(0,0,0,.35);
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  overflow-x: hidden;
  overflow-y: auto;
  font-family: Inter, ui-sans-serif, system-ui, sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at top left, rgba(56,189,248,.18), transparent 28%),
    radial-gradient(circle at top right, rgba(139,92,246,.18), transparent 24%),
    linear-gradient(135deg, var(--bg), var(--bg2));
}

.app {
  height: 100vh;
  padding: 12px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 14px;
}

.topbar h1 {
  margin: 0;
  font-size: clamp(2rem, 3vw, 3.2rem);
  letter-spacing: -.03em;
}

.ghost-btn,
.primary-btn,
.level-btn,
.category-chip,
.answer-btn,
.option-card select {
  font: inherit;
}

#screen {
  flex: 1;
  min-height: 0;
  display: grid;
}

.panel {
  height: 100%;
  min-height: 0;
  overflow: auto;
  background: var(--panel);
  backdrop-filter: blur(12px);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 18px;
}

.section-title {
  font-size: .95rem;
  text-transform: uppercase;
  letter-spacing: .12em;
  color: #c7d2fe;
}

.stage-panel,
.question-panel,
.result-box {
  display: grid;
  gap: 14px;
}

.stage-panel--difficulty {
  grid-template-rows: auto 1fr;
}

.stage-panel--category,
.stage-panel--options {
  grid-template-rows: auto 1fr auto;
}

.stage-head {
  display: flex;
  justify-content: space-between;
  align-items: start;
  gap: 12px;
}

.stage-head.compact h2,
.stage-head h2 {
  margin: 6px 0 0;
  font-size: clamp(2rem, 3.4vw, 3.6rem);
}

.level-grid,
.category-grid,
.answers-grid,
.summary-grid,
.options-grid {
  display: grid;
  gap: 14px;
}

.level-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr));
  min-height: 0;
}

.category-grid--full {
  grid-template-columns: repeat(3, minmax(0, 1fr));
  align-content: start;
}

.answers-grid--fit {
  grid-template-columns: repeat(2, minmax(0, 1fr));
  align-content: stretch;
}

.summary-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
  width: 100%;
  max-width: 900px;
}

.options-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.level-btn,
.category-chip,
.answer-btn,
.primary-btn,
.ghost-btn {
  border: 0;
  border-radius: 22px;
  cursor: pointer;
}

.level-btn,
.answer-btn,
.primary-btn {
  background: linear-gradient(135deg, var(--accent2), var(--accent), var(--accent3));
  color: white;
}

.level-btn {
  min-height: 0;
  padding: 16px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 8px;
}

.level-btn--center {
  align-items: center;
  text-align: center;
}

.level-btn__title {
  font-size: clamp(1.4rem, 1.8vw, 2rem);
  font-weight: 900;
}

.level-btn__sub {
  font-size: 1rem;
  opacity: .92;
}

.category-chip {
  min-height: 78px;
  padding: 16px;
  background: rgba(255,255,255,.08);
  color: var(--text);
  border: 1px solid rgba(255,255,255,.06);
  font-size: 1.1rem;
  font-weight: 800;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  text-align: center;
}

.category-chip.active {
  background: linear-gradient(135deg, rgba(34,197,94,.25), rgba(56,189,248,.28));
  border-color: rgba(56,189,248,.35);
}

.question-panel {
  grid-template-rows: auto auto minmax(0,1fr);
  gap: 10px;
}

.question-top {
  display: grid;
  gap: 8px;
}

.question-meta {
  display: grid;
  gap: 10px;
  color: var(--muted);
}

.compact-meta {
  grid-template-columns: repeat(2, max-content);
  align-items: center;
}

.timebar {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 10px;
  align-items: center;
}

.timebar__track {
  height: 12px;
  border-radius: 999px;
  background: rgba(255,255,255,.08);
  overflow: hidden;
}

.timebar__fill {
  height: 100%;
  background: linear-gradient(90deg, #f59e0b, #ef4444);
  width: 100%;
}

.timebar__text {
  color: #fde68a;
  font-weight: 900;
  min-width: 44px;
  text-align: right;
}

.question-text {
  font-size: clamp(1.35rem, 2.15vw, 2.7rem);
  line-height: 1.08;
  letter-spacing: -.03em;
  display: flex;
  align-items: center;
}

.fit-text {
  min-height: 0;
}

.answer-btn {
  min-height: 72px;
  padding: 12px 16px;
  display: flex;
  align-items: center;
  gap: 14px;
  text-align: left;
  font-size: clamp(1.15rem, 1.7vw, 1.8rem);
  font-weight: 800;
}

.answer-key {
  width: 44px;
  height: 44px;
  border-radius: 14px;
  background: rgba(255,255,255,.18);
  display: inline-grid;
  place-items: center;
  font-size: 1rem;
  flex: 0 0 auto;
}

.answer-btn.correct { background: linear-gradient(135deg, #15803d, #22c55e); }
.answer-btn.wrong { background: linear-gradient(135deg, #b91c1c, #ef4444); }
.answer-btn.dimmed { opacity: .55; }

.result-box {
  place-items: center;
  text-align: center;
  grid-template-rows: auto auto auto auto;
}

.trophy { font-size: 4rem; }

.result-box h2 {
  margin: 0;
  font-size: clamp(2.4rem, 4vw, 4rem);
}

.result-box p {
  margin: 0;
  color: var(--muted);
  font-size: clamp(1.05rem, 1.6vw, 1.3rem);
}

.summary-card,
.option-card {
  background: rgba(255,255,255,.06);
  border: 1px solid rgba(255,255,255,.08);
  border-radius: 22px;
  padding: 18px;
}

.summary-card {
  display: grid;
  gap: 8px;
}

.summary-card strong {
  font-size: 1.5rem;
}

.summary-card span {
  color: var(--muted);
}

 .option-card {
  display: grid;
  gap: 12px;
  font-weight: 800;
  align-content: start;
}

.option-card--stacked {
  grid-template-rows: auto auto auto;
}

.option-card input[type="checkbox"] {
  width: 28px;
  height: 28px;
}

.option-card--stacked input[type="checkbox"] {
  justify-self: start;
}

.option-card select {
  width: 100%;
  border-radius: 14px;
  border: 1px solid rgba(255,255,255,.12);
  background: rgba(255,255,255,.08);
  color: var(--text);
  padding: 14px;
  font-size: 1rem;
}

.actions-row {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}

.actions-row--spread {
  justify-content: space-between;
}

.primary-btn,
.ghost-btn {
  min-height: 60px;
  padding: 16px 22px;
  font-weight: 900;
  font-size: 1.1rem;
}

.ghost-btn {
  background: rgba(255,255,255,.06);
  color: var(--text);
  border: 1px solid rgba(255,255,255,.14);
}

.hidden { display: none !important; }

@media (max-width: 1180px) {
  .level-grid,
  .category-grid--full,
  .answers-grid--fit,
  .summary-grid,
  .options-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .compact-meta {
    grid-template-columns: repeat(2, max-content);
  }
}

@media (max-height: 520px) and (orientation: landscape) {
  .app { padding: 8px; gap: 8px; }
  .panel { padding: 12px; }
  .topbar h1 { font-size: clamp(1.7rem, 2.4vw, 2.6rem); }
  .stage-head h2, .stage-head.compact h2 { font-size: clamp(1.6rem, 2.6vw, 2.4rem); }
  .level-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 10px; }
  .category-grid--full { grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 10px; }
  .level-btn { padding: 10px 12px; min-height: 78px; }
  .level-btn__title { font-size: 1.25rem; }
  .category-chip { min-height: 62px; padding: 12px; font-size: .98rem; }
  .ghost-btn, .primary-btn { min-height: 50px; padding: 12px 16px; }
  .question-text { font-size: clamp(1.05rem, 1.65vw, 1.6rem); }
  .answers-grid--fit { gap: 8px; }
  .answer-btn { min-height: 62px; padding: 10px 14px; font-size: clamp(.95rem, 1.05vw, 1.1rem); }
  .answer-key { width: 40px; height: 40px; }
}

@media (max-width: 760px) {
  body { overflow: auto; }
  .app { height: auto; min-height: 100vh; }
  .panel { height: auto; overflow: visible; }
  .level-grid,
  .category-grid--full,
  .answers-grid--fit,
  .summary-grid,
  .options-grid,
  .compact-meta {
    grid-template-columns: 1fr;
  }
  .stage-head,
  .actions-row--spread {
    flex-direction: column;
  }
  .summary-card { padding: 14px; }
  .summary-card strong { font-size: 1.2rem; }
  .actions-row { width: 100%; }
  .actions-row .primary-btn, .actions-row .ghost-btn { width: 100%; min-height: 52px; }
}

@media (max-width: 760px) and (orientation: portrait) {
  .result-box { gap: 10px; }
  .result-box h2 { font-size: 2rem; }
  .trophy { font-size: 3rem; }
}