* { box-sizing: border-box; }
:root {
  --bg: #0f172a;
  --panel: #111827;
  --muted: #0b1020;
  --text: #e5e7eb;
  --sub: #9ca3af;
  --primary: #60a5fa;
  --primary-600: #3b82f6;
  --accent: #34d399;
  --danger: #f87171;
}
html, body { height: 100%; }
body {
  margin: 0;
  font-family: 'Inter', system-ui, -apple-system, Segoe UI, Roboto, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  color: var(--text);
  background: radial-gradient(1200px 800px at 10% 0%, #0b1228 0%, var(--bg) 50%);
}
.site-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 16px 20px; border-bottom: 1px solid #1f2937; backdrop-filter: blur(4px);
  position: sticky; top: 0; background: rgba(15, 23, 42, 0.7);
}
.site-header h1 { font-size: 18px; margin: 0; letter-spacing: 0.2px; }
nav .tab-button {
  background: transparent; color: var(--sub); border: 1px solid #233049; padding: 8px 12px; border-radius: 10px; cursor: pointer; margin-left: 8px;
}
nav .tab-button.active { color: var(--text); border-color: var(--primary); box-shadow: 0 0 0 1px rgba(96,165,250,.2); }
nav .tab-button:disabled { opacity: 0.5; cursor: not-allowed; }

main { max-width: 960px; margin: 28px auto; padding: 0 16px; }
.tab { display: none; }
.tab.active { display: block; }
.panel {
  background: linear-gradient(180deg, rgba(255,255,255,0.02), rgba(255,255,255,0.0));
  border: 1px solid #1f2937; border-radius: 16px; padding: 16px; box-shadow: 0 10px 30px rgba(0,0,0,0.25);
}
.panel.muted { opacity: 0.7; }

.controls { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }
.timer { background: #0b1224; border: 1px solid #1e293b; padding: 8px 12px; border-radius: 12px; }
.timer .time { font-variant-numeric: tabular-nums; font-weight: 700; letter-spacing: 0.5px; }
.actions button { margin-right: 8px; }

button {
  background: #0f172a; color: var(--text); border: 1px solid #233049; padding: 10px 14px; border-radius: 10px; cursor: pointer;
}
button.primary { background: linear-gradient(180deg, var(--primary), var(--primary-600)); border-color: transparent; color: #051027; font-weight: 700; }
button:disabled { opacity: 0.6; cursor: not-allowed; }
button:focus { outline: none; box-shadow: 0 0 0 2px rgba(96,165,250,.25); }

/* Button color variants */
.btn-green {
  background: linear-gradient(180deg, #34d399, #10b981);
  border-color: transparent;
  color: #052015;
  font-weight: 700;
}
.btn-green:hover { filter: brightness(1.05); }

.btn-red {
  background: linear-gradient(180deg, #f87171, #ef4444);
  border-color: transparent;
  color: #2a0707;
  font-weight: 700;
}
.btn-red:hover { filter: brightness(1.05); }

.btn-amber {
  background: linear-gradient(180deg, #fbbf24, #f59e0b);
  border-color: transparent;
  color: #2a1905;
  font-weight: 700;
}
.btn-amber:hover { filter: brightness(1.05); }

.btn-blue {
  background: linear-gradient(180deg, var(--primary), var(--primary-600));
  border-color: transparent;
  color: #051027;
  font-weight: 700;
}
.btn-blue:hover { filter: brightness(1.05); }

.btn-purple {
  background: linear-gradient(180deg, #a78bfa, #8b5cf6);
  border-color: transparent;
  color: #130a2a;
  font-weight: 700;
}
.btn-purple:hover { filter: brightness(1.05); }

/* Extra variants for Exam Style buttons */
.btn-cyan {
  background: linear-gradient(180deg, #22d3ee, #06b6d4);
  border-color: transparent;
  color: #052027;
  font-weight: 700;
}
.btn-cyan:hover { filter: brightness(1.05); }

.btn-rose {
  background: linear-gradient(180deg, #f472b6, #ec4899);
  border-color: transparent;
  color: #2a0b1d;
  font-weight: 700;
}
.btn-rose:hover { filter: brightness(1.05); }

.progress-row { display: grid; grid-template-columns: auto 1fr; align-items: center; gap: 12px; margin: 14px 0; color: var(--sub); }
.progress-bar { height: 8px; background: #0b1020; border: 1px solid #1f2937; border-radius: 999px; overflow: hidden; }
.progress-fill { height: 100%; background: linear-gradient(90deg, var(--primary), var(--accent)); width: 0; transition: width .25s ease; }

.question-card { background: radial-gradient(600px 300px at 20% 0%, rgba(52,211,153,0.07), transparent), #0b1020; border: 1px solid #1f2937; border-radius: 16px; padding: 18px; }
.topic { color: var(--accent); font-weight: 700; margin-bottom: 6px; letter-spacing: 0.3px; }
.question { font-size: 20px; line-height: 1.5; }
.bullets { margin: 8px 0 0 0; padding-left: 18px; color: var(--text); }
.bullets li { margin: 6px 0; line-height: 1.5; }

.nav-row { display: grid; grid-template-columns: 120px 1fr 120px; align-items: center; gap: 10px; margin-top: 14px; }
.dots { display: flex; gap: 6px; justify-content: center; flex-wrap: wrap; }
.dot { width: 12px; height: 12px; border-radius: 999px; background: #1f2937; border: 1px solid #334155; cursor: pointer; }
.dot.active { background: var(--primary); border-color: var(--primary); box-shadow: 0 0 0 2px rgba(96,165,250,.25); }

.help { margin-top: 16px; color: var(--sub); }
.help summary { cursor: pointer; }

.site-footer { text-align: center; color: var(--sub); padding: 28px 0; }

/* Responsive adjustments */
@media (max-width: 640px) {
  .site-header { flex-wrap: wrap; gap: 8px; }
  nav .tab-button { padding: 10px 12px; margin-left: 6px; font-size: 14px; }
  .sound-controls { gap: 6px; }
  .sound-controls input[type="range"] { width: 90px !important; }

  main { margin: 16px auto; padding: 0 12px; }
  .question { font-size: 18px; }
  .controls { gap: 10px; }
  .timer { padding: 8px 10px; }
  .actions button { margin-right: 6px; }

  /* Stack nav row vertically and make prev/next full width */
  .nav-row { grid-template-columns: 1fr; gap: 8px; }
  #p1-prev, #p1-next { width: 100%; }

  /* Larger tap targets for dots */
  .dot { width: 16px; height: 16px; }

  /* Ensure buttons are easy to tap */
  button { min-height: 44px; }
}

@media (max-width: 420px) {
  .site-header h1 { font-size: 16px; }
  nav .tab-button { flex: 1; min-width: 0; }
  .question { font-size: 17px; }
  .bullets { padding-left: 16px; }
  .progress-row { grid-template-columns: 1fr; gap: 8px; }
  .timer .time { font-size: 18px; }
  button { padding: 12px 14px; }
}