:root {
  --bg: #f6f7f9; --panel: #fff; --line: #e1e4e8; --text: #1f2933; --muted: #6b7785; --accent: #2563eb;
  --ok: #16a34a; --ok-bg: #dcfce7; --bad: #dc2626; --bad-bg: #fee2e2; --unk: #64748b; --unk-bg: #f1f5f9;
  --warn-bg: #fef9c3; --warn: #a16207;
}
* { box-sizing: border-box; }
html, body { margin: 0; }
body { font: 14px/1.65 -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif; color: var(--text); background: var(--bg); }
.topbar { padding: 8px 16px; background: #1e293b; color: #fff; display: flex; align-items: baseline; gap: 12px; flex-wrap: wrap; }
.topbar h1 { font-size: 16px; margin: 0; font-weight: 600; }
.topbar .note { font-size: 12px; color: #cbd5e1; flex: 1; }
.topbar .back { color: #fff; font-size: 13px; text-decoration: none; background: #334155; padding: 2px 12px; border-radius: 12px; }
main { max-width: 960px; margin: 0 auto; padding: 18px 16px 60px; }
.card { background: var(--panel); border: 1px solid var(--line); border-radius: 8px; padding: 14px 18px; margin-bottom: 14px; }
.card h2 { font-size: 16px; margin: 0 0 8px; }
.card h3 { font-size: 14px; margin: 10px 0 4px; }
.muted { color: var(--muted); }
.small { font-size: 12px; }
.err { color: var(--bad); }
button, .btn { font: inherit; padding: 5px 14px; border: 1px solid var(--line); border-radius: 6px; background: #fff; cursor: pointer; color: var(--text); }
button:hover { background: #f1f5f9; }
button.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
button.primary:hover { background: #1d4ed8; }
button.good { background: var(--ok); border-color: var(--ok); color: #fff; }
button.bad { background: var(--bad); border-color: var(--bad); color: #fff; }
button.good:hover { background: #15803d; } button.bad:hover { background: #b91c1c; }
button:disabled { opacity: .5; cursor: not-allowed; }
input[type=text], input[type=search], input[type=number], select { font: inherit; padding: 6px 8px; border: 1px solid var(--line); border-radius: 6px; background: #fff; }
.row { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; }
.grow { flex: 1; min-width: 160px; }

/* 开始页 */
.banner { background: #eff6ff; border: 1px solid #bfdbfe; border-radius: 8px; padding: 10px 14px; margin-bottom: 14px; }
.banner.demo { background: var(--warn-bg); border-color: #fde68a; }
.vol { border: 1px solid var(--line); border-radius: 6px; margin: 6px 0; background: #fff; }
.vol > summary { padding: 6px 12px; font-weight: 600; cursor: pointer; background: #f1f5f9; border-radius: 6px; }
.chap { margin: 0 8px 8px; }
.chap-head { display: flex; align-items: center; gap: 8px; padding: 6px 4px 2px; font-weight: 600; border-bottom: 1px solid var(--line); }
.chap-head .t { flex: 1; }
.topic-row { display: flex; align-items: center; gap: 8px; padding: 4px 4px; border-bottom: 1px solid #f0f2f4; }
.topic-row .nm { flex: 1; }
.topic-row .sec { color: var(--muted); font-size: 12px; }
.topic-row button, .chap-head button { padding: 1px 10px; font-size: 12px; }

/* 出题页 */
.progress { height: 8px; background: #e2e8f0; border-radius: 4px; overflow: hidden; margin: 6px 0 2px; }
.progress > i { display: block; height: 100%; background: var(--accent); }
.q-title { font-size: 18px; margin: 4px 0; }
.q-text { font-size: 16px; padding: 10px 14px; background: #f8fafc; border-left: 4px solid var(--accent); margin: 10px 0; white-space: pre-wrap; }
.reason { font-size: 12px; color: var(--muted); }
.ans-input { width: 100%; font-size: 16px; padding: 8px 10px; }
.notice { font-size: 12px; color: var(--warn); background: var(--warn-bg); padding: 6px 10px; border-radius: 6px; margin-top: 12px; }
.verdict { padding: 8px 12px; border-radius: 6px; margin: 10px 0; font-weight: 600; }
.verdict.ok { background: var(--ok-bg); color: #166534; }
.verdict.no { background: var(--bad-bg); color: #991b1b; }
.refans { background: #f0fdf4; border: 1px dashed var(--ok); padding: 8px 12px; border-radius: 6px; margin: 10px 0; white-space: pre-wrap; }

/* 标签 */
.tag { display: inline-block; font-size: 11px; padding: 0 8px; border-radius: 10px; margin-right: 4px; background: #eef2f7; color: #334155; vertical-align: 1px; }
.tag.weak { background: var(--bad-bg); color: #991b1b; }
.tag.mastered { background: var(--ok-bg); color: #166534; }
.tag.unknown { background: var(--unk-bg); color: var(--unk); }
.tag.root { background: var(--bad); color: #fff; }
.tag.target { background: var(--accent); color: #fff; }
.tag.ext { background: #ede9fe; color: #6d28d9; }

/* 结果页 */
.stats { display: flex; gap: 12px; flex-wrap: wrap; margin: 8px 0; }
.stat { flex: 1; min-width: 110px; padding: 8px 12px; border-radius: 8px; text-align: center; }
.stat b { display: block; font-size: 24px; }
.stat.ok { background: var(--ok-bg); } .stat.bad { background: var(--bad-bg); } .stat.unk { background: var(--unk-bg); } .stat.ask { background: #dbeafe; }
details.topic { border-bottom: 1px solid #f0f2f4; padding: 3px 0; }
details.topic > summary { cursor: pointer; padding: 2px 0; }
details.topic > .body { padding: 6px 0 8px 18px; font-size: 13px; }
.body ul { margin: 2px 0; padding-left: 20px; }
.std { margin: 4px 0; padding: 4px 8px; background: #f8fafc; border-left: 3px solid #94a3b8; }
.std code { font-size: 12px; color: #334155; }
.std .conf { font-size: 11px; color: var(--muted); margin-left: 4px; }
ol.path { padding-left: 0; list-style: none; counter-reset: step; margin: 0; }
ol.path > li { counter-increment: step; position: relative; padding-left: 34px; }
ol.path > li::before { content: counter(step); position: absolute; left: 0; top: 3px; width: 24px; height: 24px; border-radius: 12px; background: #1e293b; color: #fff; text-align: center; line-height: 24px; font-size: 12px; }
table.log { border-collapse: collapse; width: 100%; font-size: 13px; }
table.log th, table.log td { border-bottom: 1px solid var(--line); padding: 4px 8px; text-align: left; vertical-align: top; }
.svgwrap { overflow: auto; border: 1px solid var(--line); border-radius: 6px; background: #fff; }
svg.graph text { font: 13px -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif; fill: #1f2933; pointer-events: none; }
svg.graph .n rect.body { stroke-width: 1.5; }
svg.graph .n.mastered rect.body { fill: var(--ok-bg); stroke: var(--ok); }
svg.graph .n.weak rect.body { fill: var(--bad-bg); stroke: var(--bad); }
svg.graph .n.unknown rect.body { fill: var(--unk-bg); stroke: #94a3b8; stroke-dasharray: 4 3; }
svg.graph .n.target rect.body { stroke: var(--accent); stroke-width: 3.5; }
svg.graph .n text.mark { font-size: 12px; font-weight: 600; fill: #fff; }
svg.graph .e { fill: none; stroke: #64748b; stroke-width: 1.4; }
svg.graph .e.soft { stroke: #b6c0cc; }
svg.graph .e.indirect { stroke-dasharray: 5 4; }
.legend { display: flex; gap: 14px; flex-wrap: wrap; font-size: 12px; margin: 6px 0; align-items: center; }
.legend i { display: inline-block; width: 14px; height: 14px; border-radius: 3px; border: 1.5px solid; vertical-align: -2px; margin-right: 4px; }
.legend i.m { background: var(--ok-bg); border-color: var(--ok); } .legend i.w { background: var(--bad-bg); border-color: var(--bad); }
.legend i.u { background: var(--unk-bg); border-color: #94a3b8; border-style: dashed; } .legend i.t { background: #fff; border: 3px solid var(--accent); }
.site-footer { padding: 10px 16px; color: var(--muted); font-size: 12px; text-align: center; }
.site-footer a { color: var(--accent); }

@media print {
  body { background: #fff; font-size: 12px; }
  .no-print { display: none !important; }
  main { max-width: none; padding: 0; }
  .card { border: 1px solid #bbb; break-inside: avoid-page; box-shadow: none; }
  details.topic { break-inside: avoid; }
  .svgwrap { overflow: visible; border: none; }
  svg.graph { max-width: 100%; height: auto; }
  a { color: inherit; text-decoration: none; }
  select { border: none; appearance: none; -webkit-appearance: none; }
}

/* 第五轮：选择题、解析、不稳 */
.choices { display: flex; flex-direction: column; gap: 8px; margin: 8px 0; }
button.choice { text-align: left; padding: 8px 12px; font-size: 15px; white-space: pre-wrap; }
button.choice.picked { border-color: var(--accent); background: #eff6ff; box-shadow: 0 0 0 2px #bfdbfe; }
textarea.ans-input { font: inherit; font-size: 15px; padding: 8px 10px; border: 1px solid var(--line); border-radius: 6px; }
.explain { background: #eff6ff; border-left: 4px solid var(--accent); padding: 8px 12px; border-radius: 4px; margin: 10px 0; white-space: pre-wrap; }
.tag.shaky { background: #fef3c7; color: #92400e; }
.tag.diff-basic { background: #dcfce7; color: #166534; }
.tag.diff-standard { background: #dbeafe; color: #1e40af; }
.tag.diff-advanced { background: #fae8ff; color: #86198f; }
.stat.shaky { background: #fef3c7; }
svg.graph .n.shaky rect.body { fill: #fef3c7; stroke: #d97706; }
.legend i.s { background: #fef3c7; border-color: #d97706; }