:root {
  --bg: #f6f7fb;
  --card: #ffffff;
  --text: #1a1d23;
  --muted: #6b7280;
  --border: #e5e7eb;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --success: #16a34a;
  --success-bg: #dcfce7;
  --danger: #dc2626;
  --danger-bg: #fee2e2;
  --warn: #d97706;
  --accent: #e63946;
  --radius: 12px;
  --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; background: var(--bg); color: var(--text); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif; font-size: 16px; line-height: 1.5; -webkit-font-smoothing: antialiased; }
body { min-height: 100vh; display: flex; flex-direction: column; }

/* Topbar */
.topbar { background: #fff; border-bottom: 1px solid var(--border); position: sticky; top: 0; z-index: 10; }
.brand { padding: 14px 20px 6px; font-weight: 700; font-size: 18px; color: var(--accent); }
.brand span { color: var(--muted); font-weight: 400; font-size: 13px; }
.nav { display: flex; overflow-x: auto; padding: 0 12px 10px; gap: 6px; }
.nav-btn { flex: 0 0 auto; padding: 8px 14px; border-radius: 999px; border: 1px solid var(--border); background: #fff; color: var(--text); font-size: 14px; cursor: pointer; white-space: nowrap; transition: all 0.15s; }
.nav-btn:hover { background: #f3f4f6; }
.nav-btn.active { background: var(--text); color: #fff; border-color: var(--text); }

/* Main */
main { flex: 1; padding: 20px; max-width: 760px; margin: 0 auto; width: 100%; }

/* Cards */
.card { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px; margin-bottom: 14px; box-shadow: var(--shadow); }
.card h2 { margin: 0 0 14px; font-size: 18px; }
.card h3 { margin: 0 0 10px; font-size: 15px; color: var(--muted); font-weight: 500; }

/* Dashboard */
.dash-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 12px; margin-bottom: 20px; }
.stat { background: #fff; border: 1px solid var(--border); border-radius: var(--radius); padding: 14px; }
.stat-label { font-size: 12px; color: var(--muted); text-transform: uppercase; letter-spacing: 0.5px; margin-bottom: 4px; }
.stat-value { font-size: 24px; font-weight: 700; }
.stat-sub { font-size: 12px; color: var(--muted); margin-top: 2px; }
.stat-value.good { color: var(--success); }
.stat-value.bad { color: var(--danger); }

.topic-row { display: grid; grid-template-columns: 1fr 50px 100px; gap: 10px; align-items: center; padding: 8px 0; border-bottom: 1px solid var(--border); font-size: 14px; }
.topic-row:last-child { border-bottom: none; }
.topic-name { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.topic-pct { text-align: right; font-weight: 600; font-variant-numeric: tabular-nums; }
.topic-bar { height: 6px; background: var(--border); border-radius: 3px; overflow: hidden; position: relative; }
.topic-bar-fill { position: absolute; left: 0; top: 0; bottom: 0; background: var(--success); transition: width 0.3s; }
.topic-bar-fill.low { background: var(--danger); }
.topic-bar-fill.mid { background: var(--warn); }

/* Quiz */
.question { background: #fff; border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; margin-bottom: 16px; }
.q-meta { font-size: 12px; color: var(--muted); margin-bottom: 8px; display: flex; justify-content: space-between; }
.q-text { font-size: 17px; margin-bottom: 14px; }
.q-img { max-width: 100%; margin-bottom: 14px; border-radius: 8px; }
.answers { display: flex; flex-direction: column; gap: 8px; }
.ans-btn { text-align: left; padding: 12px 14px; border: 1px solid var(--border); border-radius: 10px; background: #fff; cursor: pointer; font-size: 15px; transition: all 0.1s; color: var(--text); }
.ans-btn:hover:not(:disabled) { background: #f3f4f6; border-color: #cbd5e1; }
.ans-btn:disabled { cursor: default; }
.ans-btn.correct { background: var(--success-bg); border-color: var(--success); color: var(--success); font-weight: 600; }
.ans-btn.wrong { background: var(--danger-bg); border-color: var(--danger); color: var(--danger); }
.ans-btn .idx { display: inline-block; width: 22px; height: 22px; line-height: 22px; text-align: center; background: var(--border); border-radius: 50%; font-size: 12px; margin-right: 10px; vertical-align: middle; font-weight: 600; }
.ans-btn.correct .idx { background: var(--success); color: #fff; }
.ans-btn.wrong .idx { background: var(--danger); color: #fff; }

.explanation { margin-top: 14px; padding: 14px; background: #f9fafb; border-left: 3px solid var(--primary); border-radius: 6px; font-size: 14px; color: #374151; }
.explanation strong { color: var(--text); }

/* Actions */
.actions { display: flex; gap: 10px; margin-top: 16px; flex-wrap: wrap; }
.btn { padding: 10px 18px; border-radius: 10px; border: none; background: var(--primary); color: #fff; font-size: 15px; font-weight: 500; cursor: pointer; transition: background 0.1s; }
.btn:hover { background: var(--primary-hover); }
.btn:disabled { background: #cbd5e1; cursor: not-allowed; }
.btn.secondary { background: #e5e7eb; color: var(--text); }
.btn.secondary:hover { background: #d1d5db; }
.btn.danger { background: var(--danger); }
.btn.success { background: var(--success); }
.btn.big { padding: 14px 22px; font-size: 16px; }

.link-btn { background: none; border: none; color: var(--muted); font-size: 13px; cursor: pointer; text-decoration: underline; }
.link-btn:hover { color: var(--danger); }

/* Lists */
.topic-list { list-style: none; padding: 0; margin: 0; }
.topic-list li { display: flex; justify-content: space-between; align-items: center; padding: 10px 0; border-bottom: 1px solid var(--border); cursor: pointer; }
.topic-list li:hover { background: #f9fafb; margin: 0 -8px; padding: 10px 8px; border-radius: 6px; }
.topic-list li:last-child { border-bottom: none; }
.topic-list .badge { background: var(--border); color: var(--muted); padding: 2px 8px; border-radius: 10px; font-size: 12px; font-weight: 600; }
.topic-list .badge.good { background: var(--success-bg); color: var(--success); }
.topic-list .badge.bad { background: var(--danger-bg); color: var(--danger); }
.topic-list .badge.mid { background: #fef3c7; color: var(--warn); }

/* Mock / exam */
.exam-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 16px; font-size: 14px; }
.exam-progress { display: flex; gap: 4px; flex-wrap: wrap; margin-bottom: 14px; }
.exam-dot { width: 20px; height: 20px; border-radius: 50%; background: var(--border); font-size: 11px; display: flex; align-items: center; justify-content: center; font-weight: 600; color: #fff; }
.exam-dot.correct { background: var(--success); }
.exam-dot.wrong { background: var(--danger); }
.exam-dot.current { background: var(--primary); animation: pulse 1.5s infinite; }
@keyframes pulse { 0%,100% { opacity: 1; } 50% { opacity: 0.6; } }

.timer { font-variant-numeric: tabular-nums; font-weight: 600; color: var(--muted); }
.timer.warn { color: var(--warn); }
.timer.danger { color: var(--danger); }

/* Final gate */
.gate-streak { display: flex; gap: 10px; justify-content: center; margin: 20px 0; }
.gate-cell { width: 44px; height: 44px; border-radius: 10px; background: var(--border); display: flex; align-items: center; justify-content: center; font-size: 18px; font-weight: 700; color: #fff; }
.gate-cell.done { background: var(--success); }
.gate-cell.current { background: var(--primary); animation: pulse 1.5s infinite; }

/* Footer */
.footer { padding: 14px 20px; border-top: 1px solid var(--border); background: #fff; display: flex; justify-content: space-between; align-items: center; font-size: 13px; color: var(--muted); }

/* Toasts / helpers */
.muted { color: var(--muted); font-size: 13px; }
.center { text-align: center; }
.tag { display: inline-block; background: var(--border); color: var(--muted); padding: 2px 8px; border-radius: 10px; font-size: 11px; margin-right: 4px; }

/* Pre-answer confidence */
.pre-rating { margin-bottom: 14px; padding: 12px; background: #eff6ff; border: 1px solid #bfdbfe; border-radius: 10px; }
.pre-rating-label { font-size: 13px; color: #1e40af; margin-bottom: 8px; font-weight: 600; }
.pre-rating-btns { display: flex; gap: 6px; }
.pre-btn { flex: 1; padding: 10px 6px; border: 1px solid var(--border); border-radius: 8px; background: #fff; cursor: pointer; font-size: 13px; transition: all 0.15s; }
.pre-btn:hover:not(:disabled) { background: #f3f4f6; border-color: #93c5fd; }
.pre-btn:disabled { cursor: default; opacity: 0.4; }
.pre-btn.selected { background: var(--primary); color: #fff; border-color: var(--primary); opacity: 1; }
.answers.locked { opacity: 0.4; pointer-events: none; }

/* Session break banner */
.break-banner { background: #fef3c7; border: 1px solid #fde68a; border-radius: 10px; padding: 14px; margin-bottom: 14px; display: flex; justify-content: space-between; align-items: center; gap: 12px; }
.break-banner strong { color: #92400e; }

/* Sign quiz */
.sign-quiz-img { max-width: 200px; max-height: 200px; display: block; margin: 20px auto; }
.mode-toggle { display: flex; gap: 6px; margin-bottom: 14px; }
.mode-toggle button { flex: 1; padding: 8px; border: 1px solid var(--border); background: #fff; border-radius: 8px; cursor: pointer; font-size: 13px; }
.mode-toggle button.active { background: var(--text); color: #fff; border-color: var(--text); }

/* Retry state */
.retry-hint { padding: 12px; background: #fef3c7; border-left: 3px solid var(--warn); border-radius: 6px; margin: 10px 0; font-size: 14px; color: #92400e; font-weight: 500; }

/* Mobile tweaks */
@media (max-width: 640px) {
  main { padding: 14px; }
  .card { padding: 14px; }
  .q-text { font-size: 16px; }
  .brand { padding: 12px 16px 4px; }
  .topic-row { grid-template-columns: 1fr 44px 80px; }
}