/* ============================================================
   AiC 2026 校内赛 · 备战学习站  样式表
   纯本地、无外链、无字体依赖
   ============================================================ */

:root {
  --bg: #0a1020;
  --bg-soft: #0f1830;
  --panel: #121c36;
  --panel-2: #17233f;
  --line: #24345c;
  --line-soft: #1b2947;
  --txt: #e8eefc;
  --txt-dim: #a8b6d4;
  --txt-mute: #7889ab;
  --brand: #3b82f6;
  --brand-2: #60a5fa;
  --brand-deep: #1d4ed8;
  --cyan: #22d3ee;
  --green: #34d399;
  --amber: #fbbf24;
  --red: #f87171;
  --purple: #a78bfa;
  --radius: 14px;
  --radius-sm: 9px;
  --shadow: 0 10px 30px rgba(0, 0, 0, .35);
  --maxw: 1080px;
}

html[data-theme="light"] {
  --bg: #eef2fb;
  --bg-soft: #e4eaf7;
  --panel: #ffffff;
  --panel-2: #f5f8ff;
  --line: #cfdbf3;
  --line-soft: #e2e9f8;
  --txt: #14213d;
  --txt-dim: #43537a;
  --txt-mute: #6b7ba1;
  --shadow: 0 8px 24px rgba(30, 60, 130, .12);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--txt);
  font-family: "Microsoft YaHei", "PingFang SC", "Hiragino Sans GB", "Segoe UI", system-ui, -apple-system, sans-serif;
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

body {
  background-image:
    radial-gradient(900px 500px at 12% -8%, rgba(59, 130, 246, .20), transparent 65%),
    radial-gradient(700px 420px at 100% 0%, rgba(34, 211, 238, .12), transparent 60%);
  background-attachment: fixed;
}

a { color: var(--brand-2); text-decoration: none; }
a:hover { text-decoration: underline; }

code, kbd, pre, .mono {
  font-family: Consolas, "Cascadia Mono", "Courier New", monospace;
}

/* ---------------- 布局骨架 ---------------- */
.layout { display: flex; min-height: 100vh; }

.sidebar {
  width: 274px;
  flex: 0 0 274px;
  background: linear-gradient(180deg, var(--bg-soft), var(--bg));
  border-right: 1px solid var(--line-soft);
  padding: 18px 14px 40px;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
}

.brand {
  display: flex;
  align-items: center;
  gap: 11px;
  padding: 6px 8px 16px;
  border-bottom: 1px dashed var(--line);
  margin-bottom: 14px;
}

.brand .logo {
  width: 44px; height: 44px; flex: 0 0 44px;
  border-radius: 11px;
  background: linear-gradient(135deg, var(--brand), var(--cyan));
  display: grid; place-items: center;
  font-weight: 800; font-size: 15px; color: #04122b;
  letter-spacing: .5px;
  box-shadow: 0 6px 18px rgba(59, 130, 246, .38);
}

.brand b { display: block; font-size: 15px; letter-spacing: .3px; }
.brand span { display: block; font-size: 12px; color: var(--txt-mute); }

.nav-group { margin: 16px 0 6px; padding: 0 8px; font-size: 11.5px; letter-spacing: 2px; color: var(--txt-mute); }
.nav a {
  display: flex; align-items: center; gap: 9px;
  padding: 8px 11px; margin: 3px 0;
  border-radius: var(--radius-sm);
  color: var(--txt-dim);
  font-size: 14.2px;
  text-decoration: none;
  border: 1px solid transparent;
}
.nav a:hover { background: var(--panel); color: var(--txt); text-decoration: none; }
.nav a.active {
  background: linear-gradient(90deg, rgba(59, 130, 246, .26), rgba(59, 130, 246, .04));
  border-color: rgba(96, 165, 250, .45);
  color: #fff;
  font-weight: 600;
}
html[data-theme="light"] .nav a.active { color: var(--brand-deep); }
.nav a .dot { width: 7px; height: 7px; border-radius: 50%; background: var(--line); flex: 0 0 7px; }
.nav a.active .dot { background: var(--cyan); box-shadow: 0 0 10px var(--cyan); }

.sidebar-foot { margin-top: 18px; padding: 12px 10px 0; border-top: 1px dashed var(--line); font-size: 12px; color: var(--txt-mute); }

.main { flex: 1 1 auto; min-width: 0; display: flex; flex-direction: column; }

.topbar {
  position: sticky; top: 0; z-index: 40;
  display: flex; align-items: center; gap: 12px;
  padding: 11px 22px;
  background: rgba(10, 16, 32, .82);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line-soft);
}
html[data-theme="light"] .topbar { background: rgba(255, 255, 255, .82); }

.topbar .crumb { font-size: 13.5px; color: var(--txt-dim); flex: 1 1 auto; min-width: 0; }
.topbar .crumb b { color: var(--txt); }

.btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 7px 13px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--txt);
  font-size: 13.5px; font-family: inherit;
  cursor: pointer;
  text-decoration: none;
  white-space: nowrap;
}
.btn:hover { border-color: var(--brand-2); text-decoration: none; }
.btn.primary { background: linear-gradient(135deg, var(--brand), var(--brand-deep)); border-color: transparent; color: #fff; font-weight: 600; }
.btn.ghost { background: transparent; }
.btn.sm { padding: 4px 10px; font-size: 12.5px; }
.btn[disabled] { opacity: .45; cursor: not-allowed; }

.menu-btn { display: none; }

.content { padding: 26px 30px 90px; max-width: var(--maxw); width: 100%; margin: 0 auto; }

/* ---------------- 通用排版 ---------------- */
.page-head { margin-bottom: 22px; }
.page-head .kicker {
  display: inline-block; font-size: 12px; letter-spacing: 2.5px;
  color: var(--cyan); text-transform: uppercase; margin-bottom: 6px;
}
.page-head h1 { margin: 0 0 8px; font-size: 29px; line-height: 1.35; letter-spacing: .4px; }
.page-head p { margin: 0; color: var(--txt-dim); font-size: 14.8px; }

h2 {
  font-size: 21px; margin: 34px 0 12px;
  padding-left: 12px;
  border-left: 4px solid var(--brand);
  line-height: 1.4;
}
h3 { font-size: 17px; margin: 24px 0 9px; }
h4 { font-size: 15.2px; margin: 18px 0 7px; color: var(--brand-2); }
p { margin: 9px 0; }
ul, ol { margin: 9px 0; padding-left: 22px; }
li { margin: 5px 0; }
hr { border: 0; border-top: 1px dashed var(--line); margin: 26px 0; }

strong, b { color: #fff; }
html[data-theme="light"] strong, html[data-theme="light"] b { color: #0b1730; }

/* ---------------- 卡片 / 网格 ---------------- */
.card {
  background: var(--panel);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  padding: 18px 20px;
  box-shadow: var(--shadow);
  margin: 16px 0;
}
.card.tight { padding: 14px 16px; }
.card > :first-child { margin-top: 0; }
.card > :last-child { margin-bottom: 0; }

.grid { display: grid; gap: 14px; }
.grid.c2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid.c3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid.c4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

.tile {
  display: block;
  background: var(--panel);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  padding: 16px 17px;
  text-decoration: none;
  color: var(--txt);
  transition: transform .14s ease, border-color .14s ease;
}
.tile:hover { transform: translateY(-3px); border-color: var(--brand-2); text-decoration: none; }
.tile .ico { font-size: 22px; }
.tile b { display: block; margin: 7px 0 4px; font-size: 15.5px; }
.tile span { font-size: 13.2px; color: var(--txt-dim); line-height: 1.6; display: block; }

/* ---------------- 标签 / 徽章 ---------------- */
.tag {
  display: inline-block;
  padding: 1.5px 9px;
  border-radius: 999px;
  font-size: 11.8px;
  line-height: 1.75;
  border: 1px solid var(--line);
  color: var(--txt-dim);
  background: var(--panel-2);
  margin: 0 6px 6px 0;
  white-space: nowrap;
}
.tag.blue { border-color: rgba(96, 165, 250, .5); color: #bfdbfe; background: rgba(59, 130, 246, .16); }
.tag.green { border-color: rgba(52, 211, 153, .5); color: #a7f3d0; background: rgba(16, 185, 129, .14); }
.tag.amber { border-color: rgba(251, 191, 36, .5); color: #fde68a; background: rgba(251, 191, 36, .14); }
.tag.red { border-color: rgba(248, 113, 113, .5); color: #fecaca; background: rgba(248, 113, 113, .14); }
.tag.purple { border-color: rgba(167, 139, 250, .5); color: #ddd6fe; background: rgba(167, 139, 250, .14); }
html[data-theme="light"] .tag.blue { color: #1e40af; }
html[data-theme="light"] .tag.green { color: #047857; }
html[data-theme="light"] .tag.amber { color: #92400e; }
html[data-theme="light"] .tag.red { color: #b91c1c; }
html[data-theme="light"] .tag.purple { color: #5b21b6; }

/* ---------------- 提示框 ---------------- */
.note {
  border-left: 4px solid var(--brand);
  background: rgba(59, 130, 246, .09);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 12px 15px;
  margin: 15px 0;
  font-size: 14.5px;
}
.note.warn { border-color: var(--amber); background: rgba(251, 191, 36, .1); }
.note.danger { border-color: var(--red); background: rgba(248, 113, 113, .1); }
.note.ok { border-color: var(--green); background: rgba(52, 211, 153, .1); }
.note .t { display: block; font-weight: 700; margin-bottom: 3px; color: #fff; }
html[data-theme="light"] .note .t { color: #0b1730; }

/* ---------------- 表格 ---------------- */
.table-wrap { overflow-x: auto; margin: 15px 0; border-radius: var(--radius-sm); border: 1px solid var(--line-soft); }
table { width: 100%; border-collapse: collapse; font-size: 14.2px; min-width: 520px; }
th, td { padding: 9px 12px; text-align: left; border-bottom: 1px solid var(--line-soft); vertical-align: top; }
th { background: var(--panel-2); color: var(--txt); font-weight: 600; white-space: nowrap; }
tr:last-child td { border-bottom: 0; }
tbody tr:hover { background: rgba(59, 130, 246, .06); }

/* ---------------- 代码块 ---------------- */
pre {
  background: #060c1a;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 13px 15px;
  overflow-x: auto;
  font-size: 13.4px;
  line-height: 1.65;
  color: #cfe3ff;
  margin: 12px 0;
}
html[data-theme="light"] pre { background: #0d1730; color: #d7e6ff; }
code:not(pre code) {
  background: var(--panel-2);
  border: 1px solid var(--line-soft);
  border-radius: 5px;
  padding: 1px 6px;
  font-size: 13.4px;
  color: var(--brand-2);
}

/* ---------------- 考点条目 ---------------- */
.kp { border: 1px solid var(--line-soft); border-radius: var(--radius-sm); padding: 13px 15px; margin: 11px 0; background: var(--panel-2); }
.kp > .kp-h { display: flex; align-items: center; gap: 9px; flex-wrap: wrap; margin-bottom: 6px; }
.kp > .kp-h b { font-size: 15.2px; }
.kp .kp-body { font-size: 14.4px; color: var(--txt-dim); }
.kp .kp-body strong { color: var(--txt); }

.checklist { list-style: none; padding-left: 0; }
.checklist li { display: flex; gap: 10px; align-items: flex-start; padding: 6px 0; border-bottom: 1px dashed var(--line-soft); font-size: 14.5px; }
.checklist li:last-child { border-bottom: 0; }
.checklist input { margin-top: 7px; accent-color: var(--brand); width: 16px; height: 16px; flex: 0 0 16px; }
.checklist label { cursor: pointer; flex: 1 1 auto; }

/* ---------------- 折叠 ---------------- */
details { border: 1px solid var(--line-soft); border-radius: var(--radius-sm); padding: 10px 14px; margin: 10px 0; background: var(--panel-2); }
details[open] { border-color: var(--line); }
summary { cursor: pointer; font-weight: 600; font-size: 14.8px; }
summary::marker { color: var(--brand-2); }
details > *:not(summary) { font-size: 14.4px; color: var(--txt-dim); }

/* ---------------- 进度条 ---------------- */
.bar { height: 9px; border-radius: 999px; background: var(--panel-2); border: 1px solid var(--line-soft); overflow: hidden; }
.bar > i { display: block; height: 100%; width: 0; background: linear-gradient(90deg, var(--brand), var(--cyan)); transition: width .3s ease; }

/* ---------------- 倒计时 ---------------- */
.countdown { display: flex; gap: 12px; flex-wrap: wrap; }
.countdown .cd {
  min-width: 78px; text-align: center;
  background: var(--panel-2); border: 1px solid var(--line);
  border-radius: var(--radius-sm); padding: 9px 6px;
}
.countdown .cd b { display: block; font-size: 25px; line-height: 1.15; color: var(--cyan); font-variant-numeric: tabular-nums; }
.countdown .cd span { font-size: 12px; color: var(--txt-mute); }

/* ---------------- 图片 ---------------- */
.figure { margin: 18px 0; text-align: center; }
.figure img { max-width: 100%; border-radius: var(--radius); border: 1px solid var(--line); box-shadow: var(--shadow); }
.figure figcaption { font-size: 13px; color: var(--txt-mute); margin-top: 8px; }
.img-row { display: flex; gap: 14px; flex-wrap: wrap; justify-content: center; align-items: flex-start; }
.img-row .figure { flex: 1 1 260px; max-width: 340px; }

/* ---------------- 答题引擎 ---------------- */
.quiz-shell { max-width: 860px; }
.quiz-top { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-bottom: 14px; }
.quiz-top .stat { font-size: 13.5px; color: var(--txt-dim); }
.quiz-top .stat b { color: var(--cyan); font-size: 16px; }

.qcard { background: var(--panel); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow); }
.qmeta { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; margin-bottom: 12px; }
.qtext { font-size: 17px; line-height: 1.7; margin: 6px 0 16px; font-weight: 600; }

.opts { display: grid; gap: 9px; }
.opt {
  display: flex; gap: 11px; align-items: flex-start;
  padding: 11px 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: var(--panel-2);
  cursor: pointer;
  font-size: 15px;
  text-align: left;
  color: var(--txt);
  font-family: inherit;
  width: 100%;
}
.opt:hover { border-color: var(--brand-2); }
.opt .k {
  flex: 0 0 24px; width: 24px; height: 24px; border-radius: 6px;
  background: var(--line-soft); color: var(--txt-dim);
  display: grid; place-items: center; font-weight: 700; font-size: 13px;
}
.opt.correct { border-color: var(--green); background: rgba(52, 211, 153, .16); }
.opt.correct .k { background: var(--green); color: #04122b; }
.opt.wrong { border-color: var(--red); background: rgba(248, 113, 113, .16); }
.opt.wrong .k { background: var(--red); color: #2a0505; }
.opt[disabled] { cursor: default; }

.explain { margin-top: 15px; padding: 12px 15px; border-radius: var(--radius-sm); background: rgba(34, 211, 238, .09); border: 1px dashed rgba(34, 211, 238, .45); font-size: 14.4px; }
.explain b { color: var(--cyan); }

.quiz-nav { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; margin-top: 18px; }
.quiz-nav .spacer { flex: 1 1 auto; }

.palette { display: flex; flex-wrap: wrap; gap: 7px; margin-top: 16px; }
.palette button {
  width: 34px; height: 34px; border-radius: 8px;
  border: 1px solid var(--line); background: var(--panel-2); color: var(--txt-dim);
  font-size: 12.6px; cursor: pointer; font-family: inherit;
}
.palette button.done { border-color: rgba(96, 165, 250, .6); color: var(--brand-2); }
.palette button.ok { border-color: var(--green); background: rgba(52, 211, 153, .2); color: #d1fae5; }
.palette button.no { border-color: var(--red); background: rgba(248, 113, 113, .2); color: #fee2e2; }
.palette button.cur { outline: 2px solid var(--cyan); outline-offset: 1px; }

.score-big { font-size: 54px; font-weight: 800; line-height: 1.1; }
.score-big.pass { color: var(--green); }
.score-big.fail { color: var(--red); }

.result-list { list-style: none; padding-left: 0; }
.result-list li { display: flex; gap: 10px; padding: 7px 0; border-bottom: 1px dashed var(--line-soft); font-size: 14.3px; }
.result-list .r { flex: 0 0 44px; font-weight: 700; }

/* ---------------- 首页 Hero ---------------- */
.hero {
  position: relative;
  border-radius: 18px;
  padding: 26px 28px;
  margin-bottom: 20px;
  background: linear-gradient(135deg, rgba(29, 78, 216, .38), rgba(34, 211, 238, .16));
  border: 1px solid rgba(96, 165, 250, .4);
  overflow: hidden;
}
.hero h1 { margin: 0 0 8px; font-size: 27px; letter-spacing: .5px; }
.hero p { margin: 0 0 14px; color: var(--txt-dim); font-size: 14.8px; }
.hero .hline { display: flex; gap: 9px; flex-wrap: wrap; }

/* ---------------- 页脚 ---------------- */
.foot { margin-top: 44px; padding-top: 18px; border-top: 1px dashed var(--line); font-size: 12.8px; color: var(--txt-mute); }

/* ---------------- 动画演示 ---------------- */
.anim-wrap {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 14px;
  margin: 18px 0;
  box-shadow: var(--shadow);
}
.anim-bar {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  margin-bottom: 10px;
}
.anim-bar .anim-spacer { flex: 1 1 auto; }
.anim-lab {
  display: inline-flex; align-items: center; gap: 7px;
  font-size: 12.8px; color: var(--txt-dim);
  background: var(--panel-2); border: 1px solid var(--line-soft);
  border-radius: 999px; padding: 3px 12px;
}
.anim-lab b { color: var(--cyan); font-family: Consolas, monospace; min-width: 42px; display: inline-block; }
.anim-lab input[type="range"] { width: 108px; accent-color: var(--brand); }
.anim-note { font-size: 12.6px; color: var(--txt-mute); }
.anim-wrap canvas {
  display: block; width: 100%; border-radius: var(--radius-sm);
  border: 1px solid var(--line-soft); background: #0f172a; touch-action: none;
}
.anim-pair { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
@media (max-width: 700px) { .anim-pair { grid-template-columns: 1fr; } }

.anim-steps { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 10px; }
.anim-step {
  font-family: inherit; font-size: 12.4px;
  padding: 4px 10px; border-radius: 999px;
  border: 1px solid var(--line); background: var(--panel-2); color: var(--txt-dim);
  cursor: pointer;
}
.anim-step:hover { border-color: var(--brand-2); color: var(--txt); }
.anim-step.on { background: linear-gradient(135deg, var(--brand), var(--brand-deep)); color: #fff; border-color: transparent; }

.anim-desc {
  margin-top: 10px; font-size: 14px; color: var(--txt-dim);
  border-left: 3px solid var(--cyan); padding-left: 11px;
}
.anim-desc b { color: var(--txt); }
.anim-desc code { font-size: 12.8px; }

.anim-readout {
  display: flex; gap: 16px; flex-wrap: wrap;
  margin-top: 9px; font-size: 13px; color: var(--txt-dim);
}
.anim-readout b { color: var(--cyan); font-family: Consolas, monospace; }

/* 决策树 */
.dt-node, .dt-root {
  border: 1px solid var(--line-soft); border-left: 3px solid var(--brand);
  border-radius: var(--radius-sm);
  background: var(--panel-2);
  padding: 10px 13px; margin: 9px 0;
}
.dt-root { border-left-color: var(--cyan); }
.dt-q { font-weight: 600; font-size: 14.6px; }
.dt-d { font-size: 13.6px; color: var(--txt-dim); margin-top: 4px; }
.dt-kids { padding-left: 12px; border-left: 1px dashed var(--line); margin-top: 8px; }

/* 步骤条 / 知识卡 */
.steps { counter-reset: st; padding-left: 0; list-style: none; }
.steps > li {
  counter-increment: st; position: relative;
  padding: 10px 0 10px 42px; border-bottom: 1px dashed var(--line-soft);
  font-size: 14.6px;
}
.steps > li:last-child { border-bottom: 0; }
.steps > li::before {
  content: counter(st);
  position: absolute; left: 0; top: 11px;
  width: 27px; height: 27px; border-radius: 8px;
  background: linear-gradient(135deg, var(--brand), var(--brand-deep));
  color: #fff; font-size: 13px; font-weight: 700;
  display: grid; place-items: center;
}

.kv { display: grid; grid-template-columns: 130px 1fr; gap: 4px 12px; font-size: 14.3px; margin: 10px 0; }
.kv dt { color: var(--txt-mute); }
.kv dd { margin: 0; }

.q-inline { color: var(--amber); font-weight: 600; }

/* 目录式章节导航（页面内） */
.toc {
  display: flex; flex-wrap: wrap; gap: 7px;
  padding: 11px 12px; margin: 14px 0 20px;
  border: 1px dashed var(--line); border-radius: var(--radius-sm);
  background: var(--panel-2);
}
.toc a {
  font-size: 12.8px; padding: 3px 10px; border-radius: 999px;
  border: 1px solid var(--line-soft); background: var(--panel); color: var(--txt-dim);
}
.toc a:hover { border-color: var(--brand-2); color: var(--txt); text-decoration: none; }
.toc b { font-size: 12.6px; color: var(--txt-mute); align-self: center; margin-right: 4px; }

/* 打印时动画区简化为说明 */
@media print {
  .anim-wrap { break-inside: avoid; }
  .anim-bar, .anim-steps { display: none !important; }
}

/* ---------------- 响应式 ---------------- */
@media (max-width: 980px) {
  .grid.c4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid.c3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 820px) {
  .sidebar {
    position: fixed; z-index: 60; left: 0; top: 0;
    transform: translateX(-102%);
    transition: transform .22s ease;
    box-shadow: 0 0 40px rgba(0, 0, 0, .6);
  }
  body.nav-open .sidebar { transform: translateX(0); }
  body.nav-open::after {
    content: ""; position: fixed; inset: 0; background: rgba(0, 0, 0, .5); z-index: 50;
  }
  .menu-btn { display: inline-flex; }
  .content { padding: 20px 16px 80px; }
  .grid.c2, .grid.c3, .grid.c4 { grid-template-columns: minmax(0, 1fr); }
  .page-head h1 { font-size: 23px; }
}

@media print {
  .sidebar, .topbar, .quiz-nav { display: none !important; }
  body { background: #fff; color: #000; }
  .content { max-width: none; }
}