:root {
  --bg: #f6f7f9;
  --card: #ffffff;
  --text: #1d2330;
  --muted: #6b7385;
  --border: #e2e5ea;
  --accent: #2f6fde;
  --passed: #1f9d55;
  --failed: #d64545;
  --skipped: #d39b12;
  --unread: #b3b9c4;
  --radius: 10px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14171c;
    --card: #1d2128;
    --text: #e6e8ec;
    --muted: #949bab;
    --border: #2d323b;
    --accent: #6a9cf5;
    --unread: #4a505c;
  }
}

* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}
a { color: var(--accent); }
.hidden { display: none !important; }
.muted { color: var(--muted); }
.small { font-size: 13px; }
kbd {
  font: 11px ui-monospace, monospace;
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 0 4px;
  margin-left: 4px;
  color: var(--muted);
}

/* layout */
.wrap { max-width: 860px; margin: 0 auto; padding: 16px; }
.topbar {
  position: sticky; top: 0; z-index: 5;
  display: flex; align-items: center; gap: 8px; flex-wrap: wrap;
  padding: 10px 16px;
  background: var(--card);
  border-bottom: 1px solid var(--border);
}
.topbar-title { font-weight: 600; flex: 1; text-align: center; }
.topbar-right { display: flex; gap: 8px; flex-wrap: wrap; }
.row-center { display: flex; justify-content: center; gap: 8px; margin: 14px 0; flex-wrap: wrap; }

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
  margin: 14px 0;
}

/* buttons */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 7px 14px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--card);
  color: var(--text);
  font: inherit; font-size: 14px;
  text-decoration: none;
  cursor: pointer;
  user-select: none;
}
.btn:hover { border-color: var(--accent); }
.btn.disabled { opacity: .4; pointer-events: none; }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.danger { color: var(--failed); }
.btn.ghost { border-color: transparent; color: var(--muted); }
.btn-wide { width: 100%; padding: 12px; font-size: 15px; }

/* question page */
.q-head { display: flex; align-items: center; justify-content: space-between; gap: 10px; }
.q-head h1 { font-size: 20px; margin: 10px 0 0; }
.question img, .comment-text img {
  max-width: 100%; height: auto; display: block; margin: 10px 0;
  border: 1px solid var(--border); border-radius: 6px; background: #fff;
}
.answer h2 { font-size: 15px; text-transform: uppercase; letter-spacing: .05em; color: var(--muted); margin: 0 0 10px; }
.comment { border-left: 3px solid var(--border); padding: 4px 0 4px 12px; margin: 10px 0; }
.comment.top { border-left-color: var(--accent); }
.comment-meta { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; margin-bottom: 4px; }
.comment-text { overflow-wrap: anywhere; }
details.more summary { cursor: pointer; color: var(--muted); margin-top: 8px; }
.votes { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; margin-bottom: 8px; font-size: 14px; }
.pill {
  font-size: 12px; padding: 1px 8px; border-radius: 999px;
  background: var(--bg); border: 1px solid var(--border);
}
.pill-answer { border-color: var(--accent); color: var(--accent); font-weight: 600; }

.grade { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; margin-top: 14px; }
.grade-btn { padding: 12px 6px; font-weight: 600; }
.grade-btn.passed { color: var(--passed); }
.grade-btn.failed { color: var(--failed); }
.grade-btn.skipped { color: var(--skipped); }
.grade-btn.current.passed { background: var(--passed); color: #fff; border-color: var(--passed); }
.grade-btn.current.failed { background: var(--failed); color: #fff; border-color: var(--failed); }
.grade-btn.current.skipped { background: var(--skipped); color: #fff; border-color: var(--skipped); }

.status-badge { font-size: 12px; font-weight: 600; padding: 2px 10px; border-radius: 999px; color: #fff; background: var(--unread); white-space: nowrap; }
.status-badge.passed { background: var(--passed); }
.status-badge.failed { background: var(--failed); }
.status-badge.skipped { background: var(--skipped); }

/* index / dashboard */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; }
.stat { text-align: center; }
.stat-num { font-size: 26px; font-weight: 700; }
.stat-label { font-size: 13px; color: var(--muted); }
.stat.passed .stat-num { color: var(--passed); }
.stat.failed .stat-num { color: var(--failed); }
.stat.skipped .stat-num { color: var(--skipped); }
.bar { display: flex; height: 10px; border-radius: 999px; overflow: hidden; background: var(--unread); margin-top: 14px; }
.seg { display: block; height: 100%; transition: width .3s; }
.seg.passed { background: var(--passed); }
.seg.failed { background: var(--failed); }
.seg.skipped { background: var(--skipped); }

.filters { display: flex; gap: 6px; flex-wrap: wrap; margin: 6px 0 4px; }
.chip {
  font: inherit; font-size: 13px; padding: 4px 12px; border-radius: 999px; cursor: pointer;
  border: 1px solid var(--border); background: var(--card); color: var(--text);
}
.chip.active { background: var(--accent); border-color: var(--accent); color: #fff; }

h2.topic { font-size: 16px; margin: 22px 0 6px; color: var(--muted); }
.qlist { list-style: none; margin: 0; padding: 0; background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
.qlist li + li { border-top: 1px solid var(--border); }
.qlist a { display: flex; align-items: center; gap: 10px; padding: 8px 14px; color: var(--text); text-decoration: none; }
.qlist a:hover { background: var(--bg); }
.qlist li.last a { box-shadow: inset 3px 0 var(--accent); }
.dot { width: 10px; height: 10px; border-radius: 50%; flex: none; background: var(--unread); }
.st-passed .dot { background: var(--passed); }
.st-failed .dot { background: var(--failed); }
.st-skipped .dot { background: var(--skipped); }
.qnum { font-weight: 600; min-width: 44px; }
.qpreview { color: var(--muted); font-size: 14px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }

@media (max-width: 560px) {
  .stats { grid-template-columns: repeat(2, 1fr); }
  .topbar-title { order: -1; flex-basis: 100%; }
  .grade { grid-template-columns: 1fr; }
}