:root {
  --bg: #f6f7fb;
  --bg-card: #ffffff;
  --bg-soft: #eef1f7;
  --text: #1c2130;
  --muted: #6b7385;
  --border: #dde2ec;
  --primary: #2f63e8;
  --primary-soft: #e4ecff;
  --ok: #1f9d55;
  --ok-soft: #dff5e8;
  --bad: #d64545;
  --bad-soft: #fde3e3;
  --warn: #e08a12;
  --warn-soft: #fff1d6;
  --star: #f0a020;
  --shadow: 0 1px 3px rgba(20, 30, 60, 0.08);
  --radius: 10px;
  --font: -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", Roboto, sans-serif;
}
:root[data-theme="dark"] {
  --bg: #12151c;
  --bg-card: #1b1f29;
  --bg-soft: #232838;
  --text: #e6e9f0;
  --muted: #9aa3b8;
  --border: #303748;
  --primary: #6b93ff;
  --primary-soft: #253358;
  --ok: #4ccd7e;
  --ok-soft: #1e3a2a;
  --bad: #ff6b6b;
  --bad-soft: #43242a;
  --warn: #f3b04b;
  --warn-soft: #3f3220;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.4);
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.65;
  color: var(--text);
  background: var(--bg);
}
a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }
h1 { font-size: 1.7rem; margin: 0.4em 0 0.6em; }
h2 { font-size: 1.3rem; margin: 1.4em 0 0.6em; }
h3 { font-size: 1.1rem; margin: 0.6em 0 0.4em; }
h4 { margin: 0.6em 0 0.4em; font-size: 1rem; }
h5 { margin: 0.6em 0 0.2em; font-size: 0.95rem; color: var(--muted); }
.h-sub { font-size: 1rem; font-weight: 400; }
.muted { color: var(--muted); }
.small { font-size: 0.85rem; }
.big { font-size: 1.8rem; font-weight: 600; }
.ok { color: var(--ok); }
.bad { color: var(--bad); }
.warn-text { color: var(--warn); font-weight: 600; }
code { background: var(--bg-soft); padding: 0 0.3em; border-radius: 4px; font-size: 0.92em; }
.tex-error { color: var(--bad); }

/* ---------- 布局 ---------- */
.topbar {
  position: sticky; top: 0; z-index: 20;
  background: var(--bg-card);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow);
}
.topbar-inner {
  max-width: 1100px; margin: 0 auto; padding: 0 16px;
  display: flex; align-items: center; gap: 16px; height: 52px;
}
.brand { font-weight: 700; white-space: nowrap; }
.brand span { color: var(--primary); }
.nav { display: flex; gap: 4px; flex: 1; overflow-x: auto; }
.nav a {
  padding: 6px 12px; border-radius: 8px; color: var(--text); white-space: nowrap;
}
.nav a:hover { background: var(--bg-soft); text-decoration: none; }
.nav a.active { background: var(--primary-soft); color: var(--primary); font-weight: 600; }
#theme-toggle {
  border: 1px solid var(--border); background: var(--bg-card); color: var(--text);
  border-radius: 8px; padding: 4px 10px; cursor: pointer;
}
.view { max-width: 1100px; margin: 0 auto; padding: 16px 16px 60px; }

/* ---------- 通用组件 ---------- */
.card {
  background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px 18px; margin: 12px 0; box-shadow: var(--shadow);
}
.card.notice { border-color: var(--warn); background: var(--warn-soft); }
.grid2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 12px; }
.grid3 { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 12px; }
.row { display: flex; align-items: center; }
.gap { gap: 10px; }
.wrap { flex-wrap: wrap; }
.btn {
  display: inline-block; border: 1px solid var(--border); background: var(--bg-card); color: var(--text);
  padding: 8px 16px; border-radius: 8px; cursor: pointer; font-size: 0.95rem; line-height: 1.3;
  transition: background 0.15s;
}
.btn:hover { background: var(--bg-soft); text-decoration: none; }
.btn.primary { background: var(--primary); border-color: var(--primary); color: #fff; }
.btn.primary:hover { filter: brightness(1.08); }
.btn.ghost { background: transparent; }
.btn.danger { color: var(--bad); border-color: var(--bad); }
.btn.small { padding: 4px 10px; font-size: 0.85rem; }
.btn:disabled { opacity: 0.45; cursor: not-allowed; }
.btn.on { background: var(--warn-soft); border-color: var(--warn); }
.sel, .num, input[type="date"] {
  border: 1px solid var(--border); background: var(--bg-card); color: var(--text);
  border-radius: 6px; padding: 6px 8px; font-size: 0.95rem;
}
.num { width: 80px; }
.table { width: 100%; border-collapse: collapse; margin: 8px 0; background: var(--bg-card); border-radius: var(--radius); overflow: hidden; }
.table th, .table td { padding: 8px 10px; border-bottom: 1px solid var(--border); text-align: left; vertical-align: top; }
.table th { background: var(--bg-soft); font-weight: 600; font-size: 0.9rem; }
.table tr:last-child td { border-bottom: none; }
.tag {
  display: inline-block; font-size: 0.75rem; padding: 1px 8px; border-radius: 999px;
  background: var(--bg-soft); color: var(--muted); margin-right: 4px;
}
.tag.sheet { background: var(--primary-soft); color: var(--primary); }
.tag.memo { background: var(--warn-soft); color: var(--warn); }
.plain-list { padding-left: 1.2em; }
.crumb { color: var(--muted); font-size: 0.9rem; margin-top: 6px; }
.stars { color: var(--star); letter-spacing: 1px; font-size: 0.9em; white-space: nowrap; }
.stars-dim { opacity: 0.25; }
.bar { height: 8px; background: var(--bg-soft); border-radius: 4px; overflow: hidden; }
.bar-fill { height: 100%; background: var(--primary); transition: width 0.3s; }
.bar.small { height: 6px; }
.inline-bar { display: inline-block; width: 80px; vertical-align: middle; }
details.note-sec { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); margin: 10px 0; }
details.note-sec summary { padding: 10px 16px; cursor: pointer; font-weight: 600; list-style: none; }
details.note-sec summary::before { content: "▸ "; color: var(--muted); }
details.note-sec[open] summary::before { content: "▾ "; }
details.note-sec > *:not(summary) { padding: 0 16px 12px; }
details.pitfalls { border-color: var(--warn); }
.tabs { display: flex; gap: 4px; border-bottom: 1px solid var(--border); margin: 8px 0 12px; }
.tab { border: none; background: transparent; color: var(--muted); padding: 8px 14px; cursor: pointer; border-bottom: 2px solid transparent; font-size: 0.95rem; }
.tab.active { color: var(--primary); border-bottom-color: var(--primary); font-weight: 600; }

/* ---------- 公式 ---------- */
.math-display { margin: 0.6em 0; overflow-x: auto; }
.katex { font-size: 1.05em; }
.f-tex { white-space: nowrap; }
.formulas td { vertical-align: middle; }
.formula-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); gap: 12px; }
.formula-grid .card { margin: 0; }

/* ---------- 首页 ---------- */
.tiles { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 12px; margin: 12px 0; }
.tile { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 12px 16px; }
.countdown { font-size: 1.1rem; }
.mastery-list { display: flex; flex-direction: column; gap: 6px; }
.mastery-row {
  display: grid; grid-template-columns: 40px 1fr 200px 50px 80px; gap: 10px; align-items: center;
  background: var(--bg-card); border: 1px solid var(--border); border-radius: 8px; padding: 8px 14px; color: var(--text);
}
.mastery-row:hover { text-decoration: none; background: var(--bg-soft); }
.m-id { font-weight: 700; color: var(--primary); }
.m-pct { text-align: right; font-weight: 600; }
.unit-card { display: block; color: var(--text); }
.unit-card:hover { text-decoration: none; border-color: var(--primary); }
.u-id { font-weight: 700; color: var(--primary); }
.u-counts { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 8px; font-size: 0.85rem; color: var(--muted); }

/* ---------- 题卡 ---------- */
.qcard { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px 20px; margin: 12px 0; box-shadow: var(--shadow); }
.qcard.unanswered { border-left: 4px solid var(--warn); }
.q-head { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 8px; margin-bottom: 8px; }
.q-meta { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; font-size: 0.85rem; color: var(--muted); }
.q-index { font-weight: 700; color: var(--text); font-size: 1rem; }
.q-id { font-family: ui-monospace, Consolas, monospace; }
.q-pts { background: var(--bg-soft); padding: 0 8px; border-radius: 999px; }
.q-marks { display: flex; gap: 6px; }
.mark { border: 1px solid var(--border); background: transparent; color: var(--muted); border-radius: 999px; padding: 2px 10px; cursor: pointer; font-size: 0.8rem; }
.mark.on { background: var(--warn-soft); color: var(--warn); border-color: var(--warn); }
.q-stem { font-size: 1.02rem; }
.q-stem p { margin: 0.5em 0; }
.q-figure { margin: 10px 0; text-align: center; }
.q-figure svg { max-width: 100%; height: auto; max-height: 320px; color: var(--text); }
.choices { list-style: none; padding: 0; margin: 12px 0 0; display: flex; flex-direction: column; gap: 8px; }
.choice {
  width: 100%; text-align: left; display: flex; gap: 12px; align-items: flex-start;
  border: 1px solid var(--border); background: var(--bg-card); color: var(--text);
  border-radius: 8px; padding: 10px 14px; cursor: pointer; font-size: 1rem; line-height: 1.5;
}
.choice:hover:not(:disabled) { border-color: var(--primary); background: var(--bg-soft); }
.choice:disabled { cursor: default; }
.choice .letter { font-weight: 700; color: var(--muted); min-width: 1.4em; }
.choice-body p { margin: 0; display: inline; }
.choice.chosen { border-color: var(--primary); background: var(--primary-soft); }
.choice.correct { border-color: var(--ok); background: var(--ok-soft); }
.choice.correct .letter { color: var(--ok); }
.choice.wrong { border-color: var(--bad); background: var(--bad-soft); }
.choice.wrong .letter { color: var(--bad); }
.q-solution { margin-top: 16px; padding: 12px 16px; background: var(--bg-soft); border-radius: 8px; border-left: 3px solid var(--primary); }
.q-solution h4 { margin-top: 0; }
.verdict { font-weight: 600; margin-bottom: 8px; }
.verdict.ok { color: var(--ok); }
.verdict.bad { color: var(--bad); }
.q-pitfall { margin-top: 10px; padding: 8px 12px; background: var(--warn-soft); border-radius: 6px; }
.q-pitfall p { display: inline; margin: 0; }
.q-tags { margin-top: 8px; }
.frq-parts { margin-top: 12px; display: flex; flex-direction: column; gap: 10px; }
.frq-part { border: 1px solid var(--border); border-radius: 8px; padding: 10px 14px; }
.part-prompt { position: relative; padding-right: 60px; }
.part-prompt p { margin: 0.3em 0; }
.part-label { font-weight: 700; color: var(--primary); }
.part-pts { position: absolute; right: 0; top: 0; font-size: 0.8rem; color: var(--muted); background: var(--bg-soft); padding: 0 8px; border-radius: 999px; }
.part-solution { margin-top: 10px; padding: 10px 12px; background: var(--bg-soft); border-radius: 6px; }
.part-solution h5 { margin-top: 0.2em; }
.rubric ul { margin: 0.2em 0; padding-left: 1.3em; }
.score-row { display: flex; align-items: center; gap: 6px; margin-top: 8px; font-weight: 600; }
.score-input { width: 64px; border: 1px solid var(--border); border-radius: 6px; padding: 4px 6px; background: var(--bg-card); color: var(--text); }
.frq-actions { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; margin: 8px 0; }
.frq-status { color: var(--muted); }

/* ---------- 会话 ---------- */
.session-top { display: flex; align-items: center; gap: 16px; padding: 8px 0; }
.session-title { font-weight: 700; flex: 1; }
.session-nav { display: flex; gap: 10px; justify-content: space-between; margin: 12px 0; flex-wrap: wrap; }
.session-summary { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 24px; margin: 16px 0; }

/* ---------- 练习筛选 ---------- */
.filter-sec { margin: 10px 0 14px; }
.filter-label { font-weight: 600; margin-bottom: 4px; }
.check-row { display: flex; flex-wrap: wrap; gap: 6px 14px; }
.chk { display: inline-flex; align-items: center; gap: 2px; cursor: pointer; }
.course-chk { font-weight: 600; }
label.inline { display: inline-flex; align-items: center; gap: 6px; }

/* ---------- 模考 ---------- */
.exam-bar {
  position: sticky; top: 52px; z-index: 10; display: flex; align-items: center; gap: 14px;
  background: var(--bg-card); border: 1px solid var(--border); border-radius: 8px; padding: 8px 14px; margin: 8px 0 12px;
}
.exam-label { flex: 1; font-weight: 600; }
.exam-timer { font-family: ui-monospace, Consolas, monospace; font-size: 1.3rem; font-weight: 700; }
.exam-timer.warn { color: var(--bad); }
.exam-layout { display: grid; grid-template-columns: 1fr 220px; gap: 16px; }
.exam-side { position: sticky; top: 112px; align-self: start; }
.qgrid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 6px; margin: 8px 0; }
.qcell { border: 1px solid var(--border); background: var(--bg-card); color: var(--text); border-radius: 6px; padding: 6px 0; cursor: pointer; font-size: 0.85rem; }
.qcell.done { background: var(--primary-soft); border-color: var(--primary); color: var(--primary); }
.qcell.flag { background: var(--warn-soft); border-color: var(--warn); }
.qcell.cur { outline: 2px solid var(--primary); }
.report-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 16px; text-align: center; }
.big.ap { color: var(--primary); font-size: 2.6rem; }
.sticky-bottom { position: sticky; bottom: 12px; background: var(--bg); padding: 10px 0; }

/* ---------- 统计 ---------- */
.bars { display: flex; align-items: flex-end; gap: 6px; height: 140px; padding: 8px; background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); }
.bar-col { flex: 1; height: 100%; display: flex; flex-direction: column; justify-content: flex-end; align-items: center; }
.bar-stack { width: 70%; background: var(--primary-soft); border-radius: 4px 4px 0 0; display: flex; flex-direction: column; justify-content: flex-end; overflow: hidden; }
.bar-ok { background: var(--primary); }
.bar-lab { font-size: 0.7rem; color: var(--muted); margin-top: 4px; }
.set-row { display: flex; align-items: center; gap: 14px; margin: 8px 0; }
.set-row label { min-width: 200px; }

@media (max-width: 720px) {
  .exam-layout { grid-template-columns: 1fr; }
  .exam-side { position: static; }
  .mastery-row { grid-template-columns: 36px 1fr 60px; }
  .mastery-row .bar, .mastery-row .muted { display: none; }
  .set-row { flex-direction: column; align-items: flex-start; }
}