:root {
  --bg: #14151d;
  --panel: #1e1f2b;
  --card: #262838;
  --card-hover: #2f3145;
  --border: #383b52;
  --text: #f2f2f5;
  --muted: #9a9db0;
  --accent: #ff9f43;
  --accent-dim: rgba(255,159,67,0.15);
  --good: #4ade80;
  --good-dim: rgba(74,222,128,0.15);
  --bad: #f87171;
  --bad-dim: rgba(248,113,113,0.15);
  --skip: #64748b;
  --skip-dim: rgba(100,116,139,0.18);
  --marked: #a78bfa;
  --marked-dim: rgba(167,139,250,0.18);
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
  min-height: 100vh;
}
#app { max-width: 1100px; margin: 0 auto; padding: 20px 16px 60px; }

h1, h2, h3 { margin: 0 0 8px; }
p { margin: 4px 0; color: var(--muted); }
a { color: var(--accent); }

.topbar {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: 24px; flex-wrap: wrap; gap: 12px;
}
.topbar .brand { font-size: 22px; font-weight: 700; }
.topbar .brand span { color: var(--accent); }
.topbar nav { display: flex; gap: 8px; flex-wrap: wrap; }

button, .btn {
  font-family: inherit; font-size: 14px; border: none; border-radius: 10px;
  padding: 10px 16px; cursor: pointer; background: var(--card); color: var(--text);
  transition: background 0.12s ease, transform 0.05s ease;
}
button:hover, .btn:hover { background: var(--card-hover); }
button:active, .btn:active { transform: scale(0.97); }
.btn-outline { background: transparent; border: 1px solid var(--border); }
.btn-accent { background: var(--accent); color: #14151d; font-weight: 600; }
.btn-accent:hover { background: #ffb976; }
.btn-danger { background: var(--bad-dim); color: var(--bad); }
.btn-sm { padding: 6px 12px; font-size: 13px; }
.btn:disabled { opacity: 0.4; cursor: not-allowed; }

.stat-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 12px; margin-bottom: 24px; }
.stat-card { background: var(--panel); border: 1px solid var(--border); border-radius: 14px; padding: 16px; }
.stat-card .num { font-size: 26px; font-weight: 700; }
.stat-card .lbl { font-size: 13px; color: var(--muted); }

.section { background: var(--panel); border: 1px solid var(--border); border-radius: 16px; padding: 20px; margin-bottom: 20px; }
.section-head { display: flex; align-items: center; justify-content: space-between; margin-bottom: 14px; flex-wrap: wrap; gap: 8px; }

.tabs { display: flex; gap: 4px; border-bottom: 1px solid var(--border); margin-bottom: 18px; flex-wrap: wrap; }
.tab { padding: 10px 16px; cursor: pointer; color: var(--muted); border-bottom: 2px solid transparent; }
.tab.active { color: var(--accent); border-bottom-color: var(--accent); }

.filter-row { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 14px; }
.filter-row select, .filter-row input[type="text"] {
  background: var(--card); border: 1px solid var(--border); color: var(--text);
  border-radius: 8px; padding: 8px 10px; font-family: inherit; font-size: 13px;
}

.mock-list { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 12px; max-height: 480px; overflow-y: auto; padding-right: 4px; }
.mock-card { background: var(--card); border: 1px solid var(--border); border-radius: 12px; padding: 14px; display: flex; flex-direction: column; gap: 6px; }
.mock-card .name { font-weight: 600; font-size: 14px; }
.mock-card .tags { display: flex; gap: 6px; flex-wrap: wrap; }
.pill { font-size: 11px; padding: 3px 8px; border-radius: 999px; background: var(--accent-dim); color: var(--accent); }
.pill.muted { background: rgba(255,255,255,0.06); color: var(--muted); }

.builder-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 16px; }
.field label { display: block; font-size: 13px; color: var(--muted); margin-bottom: 6px; }
.chip-group { display: flex; gap: 8px; flex-wrap: wrap; }
.chip {
  padding: 8px 14px; border-radius: 999px; background: var(--card); border: 1px solid var(--border);
  cursor: pointer; font-size: 13px; color: var(--muted);
}
.chip.selected { background: var(--accent-dim); border-color: var(--accent); color: var(--accent); }
.field input[type="number"] {
  width: 100%; background: var(--card); border: 1px solid var(--border); color: var(--text);
  border-radius: 8px; padding: 10px; font-family: inherit; font-size: 14px;
}
.topic-list { max-height: 160px; overflow-y: auto; display: flex; flex-direction: column; gap: 4px; border: 1px solid var(--border); border-radius: 8px; padding: 8px; }
.topic-list label { display: flex; align-items: center; gap: 8px; font-size: 13px; color: var(--text); cursor: pointer; }
.pool-note { font-size: 13px; color: var(--muted); margin-top: 12px; }

.history-table { width: 100%; border-collapse: collapse; font-size: 13px; }
.history-table th, .history-table td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border); }
.history-table th { color: var(--muted); font-weight: 500; }
.history-table tr:hover td { background: rgba(255,255,255,0.02); }

.weak-list { display: flex; flex-direction: column; gap: 8px; }
.weak-row { display: flex; align-items: center; gap: 10px; }
.weak-row .name { width: 200px; font-size: 13px; flex-shrink: 0; }
.bar-track { flex: 1; height: 10px; background: rgba(255,255,255,0.06); border-radius: 6px; overflow: hidden; }
.bar-fill { height: 100%; border-radius: 6px; }
.weak-row .pct { width: 44px; text-align: right; font-size: 13px; color: var(--muted); flex-shrink: 0; }

.empty-hint { color: var(--muted); font-size: 14px; padding: 20px; text-align: center; }

/* Exam screen */
.exam-shell { display: grid; grid-template-columns: 1fr 300px; gap: 20px; align-items: start; }
@media (max-width: 800px) { .exam-shell { grid-template-columns: 1fr; } }
.exam-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: 16px; flex-wrap: wrap; gap: 10px; }
.timer { font-size: 20px; font-weight: 700; font-variant-numeric: tabular-nums; padding: 8px 16px; background: var(--card); border-radius: 10px; }
.timer.low { color: var(--bad); }
.question-box { background: var(--panel); border: 1px solid var(--border); border-radius: 16px; padding: 22px; }
.q-meta { display: flex; gap: 8px; margin-bottom: 12px; align-items: center; flex-wrap: wrap; }
.q-text { font-size: 17px; line-height: 1.5; margin-bottom: 18px; white-space: pre-wrap; }
.option {
  display: flex; align-items: flex-start; gap: 10px; padding: 12px 14px; border-radius: 10px;
  border: 1px solid var(--border); background: var(--card); margin-bottom: 10px; cursor: pointer; font-size: 14.5px;
}
.option:hover { background: var(--card-hover); }
.option.selected { border-color: var(--accent); background: var(--accent-dim); }
.option .radio { width: 18px; height: 18px; border-radius: 50%; border: 2px solid var(--border); flex-shrink: 0; margin-top: 1px; }
.option.selected .radio { border-color: var(--accent); background: radial-gradient(circle, var(--accent) 0 40%, transparent 45%); }
.exam-actions { display: flex; justify-content: space-between; margin-top: 16px; flex-wrap: wrap; gap: 8px; }
.exam-actions .left, .exam-actions .right { display: flex; gap: 8px; flex-wrap: wrap; }

.side-panel { background: var(--panel); border: 1px solid var(--border); border-radius: 16px; padding: 16px; }
.legend { display: flex; flex-wrap: wrap; gap: 8px; font-size: 11px; margin-bottom: 12px; }
.legend .dot { display: inline-block; width: 9px; height: 9px; border-radius: 50%; margin-right: 4px; }
.palette { display: grid; grid-template-columns: repeat(5, 1fr); gap: 6px; max-height: 360px; overflow-y: auto; }
.palette button {
  padding: 0; height: 34px; border-radius: 8px; font-size: 12px; font-weight: 600;
  background: var(--card); color: var(--text); border: 1px solid var(--border);
}
.palette button.current { outline: 2px solid var(--text); }
.palette button.answered { background: var(--good-dim); color: var(--good); border-color: var(--good); }
.palette button.marked { background: var(--marked-dim); color: var(--marked); border-color: var(--marked); }
.palette button.answered-marked { background: linear-gradient(135deg, var(--good-dim) 50%, var(--marked-dim) 50%); color: var(--text); border-color: var(--marked); }
.palette button.unanswered { background: var(--skip-dim); color: var(--skip); }

/* Results screen */
.score-hero { display: flex; align-items: center; gap: 24px; flex-wrap: wrap; }
.score-ring { width: 120px; height: 120px; border-radius: 50%; display: flex; align-items: center; justify-content: center; flex-direction: column; background: conic-gradient(var(--accent) calc(var(--pct) * 1%), rgba(255,255,255,0.08) 0); flex-shrink: 0; }
.score-ring .inner { width: 92px; height: 92px; border-radius: 50%; background: var(--panel); display: flex; align-items: center; justify-content: center; flex-direction: column; }
.score-ring .big { font-size: 22px; font-weight: 700; }
.score-ring .small { font-size: 11px; color: var(--muted); }
.metric-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(110px, 1fr)); gap: 10px; flex: 1; }
.metric { background: var(--card); border-radius: 10px; padding: 10px 12px; }
.metric .v { font-size: 18px; font-weight: 700; }
.metric .k { font-size: 11px; color: var(--muted); }

.summary-text { font-size: 14.5px; line-height: 1.7; background: var(--card); border-left: 3px solid var(--accent); padding: 14px 18px; border-radius: 8px; }

.review-filters { display: flex; gap: 6px; margin-bottom: 14px; flex-wrap: wrap; }
.review-item { border: 1px solid var(--border); border-radius: 12px; padding: 14px 16px; margin-bottom: 10px; }
.review-item .tag-correct { color: var(--good); }
.review-item .tag-wrong { color: var(--bad); }
.review-item .tag-skip { color: var(--skip); }
.review-opt { padding: 8px 10px; border-radius: 8px; margin-top: 4px; font-size: 13.5px; }
.review-opt.correct { background: var(--good-dim); color: var(--good); }
.review-opt.wrong-chosen { background: var(--bad-dim); color: var(--bad); }
.review-explain { margin-top: 8px; font-size: 13px; color: var(--muted); background: rgba(255,255,255,0.03); padding: 10px 12px; border-radius: 8px; }

.footer-note { text-align: center; color: var(--muted); font-size: 12px; margin-top: 30px; }