/* ============================================================
   考研数学刷题系统 — 基于 open-design 设计语言
   中性色承载体 + 品牌绿点缀、明暗双主题、统一圆角/阴影/动效 token
   ============================================================ */
:root {
  --bg: #fff;
  --bg-app: #fff;
  --bg-panel: #fafafa;
  --bg-subtle: #ededed;
  --bg-muted: #dbdbdb;
  --bg-fill-tertiary: rgba(0, 0, 0, 0.03);
  --bg-fill-secondary: rgba(0, 0, 0, 0.06);
  --bg-fill: rgba(0, 0, 0, 0.12);
  --border: #dbdbdb;
  --border-strong: #bdbdbd;
  --border-soft: #ededed;

  --text: #494949;
  --text-strong: #202020;
  --text-muted: #5c5c5c;
  --text-soft: #848484;
  --text-faint: #bdbdbd;

  --accent: #353535;
  --accent-contrast: #fafafa;
  --accent-soft: #ededed;
  --accent-tint: #f7f7f7;
  --brand: #87ea5c;
  --brand-weak: #d0ffb5;
  --brand-soft: #ebffde;
  --brand-text: #0d5400;

  --green: #00AA54;
  --green-bg: #f5ffee;
  --green-border: #adf788;
  --blue: #1A74FF;
  --blue-bg: color-mix(in srgb, #1A74FF 10%, #fafafa);
  --blue-border: color-mix(in srgb, #1A74FF 24%, #dbdbdb);
  --red: #F04142;
  --red-bg: color-mix(in srgb, #F04142 10%, #fafafa);
  --red-border: color-mix(in srgb, #F04142 24%, #dbdbdb);
  --amber: #FF7528;
  --amber-bg: color-mix(in srgb, #FFBA12 18%, #fafafa);
  --purple: #7a5af8;
  --purple-bg: color-mix(in srgb, #7a5af8 10%, #fafafa);

  --shadow-xs: 0 1px 0 rgba(28, 27, 26, 0.04);
  --shadow-sm: 0 1px 2px rgba(28, 27, 26, 0.05), 0 1px 3px rgba(28, 27, 26, 0.04);
  --shadow-md: 0 6px 24px rgba(28, 27, 26, 0.07), 0 2px 6px rgba(28, 27, 26, 0.04);
  --shadow-lg: 0 24px 60px rgba(28, 27, 26, 0.16), 0 8px 16px rgba(28, 27, 26, 0.07);

  --radius-sm: 4px;
  --radius: 8px;
  --radius-lg: 12px;
  --radius-pill: 999px;

  --dur-quick: 100ms;
  --dur-enter: 200ms;
  --ease-out: cubic-bezier(0, 0, 0, 1);

  --sans: "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;
  --mono: ui-monospace, "SFMono-Regular", Consolas, monospace;

  --nav-w: 200px;
}
[data-theme="dark"] {
  color-scheme: dark;
  --bg: #202020;
  --bg-app: #202020;
  --bg-panel: #353535;
  --bg-subtle: #494949;
  --bg-muted: #5c5c5c;
  --bg-fill-tertiary: rgba(255, 255, 255, 0.06);
  --bg-fill-secondary: rgba(255, 255, 255, 0.10);
  --bg-fill: rgba(255, 255, 255, 0.16);
  --border: #5c5c5c;
  --border-strong: #848484;
  --border-soft: #494949;

  --text: #ededed;
  --text-strong: #fafafa;
  --text-muted: #bdbdbd;
  --text-soft: #848484;
  --text-faint: #5c5c5c;

  --accent: #ededed;
  --accent-contrast: #202020;
  --accent-soft: #494949;
  --accent-tint: #353535;
  --brand: #87ea5c;
  --brand-weak: #2f781d;
  --brand-soft: #164111;
  --brand-text: #adf788;

  --green: #3BBF7D;
  --green-bg: #164111;
  --green-border: #2f781d;
  --blue: #3AA5F0;
  --blue-bg: color-mix(in srgb, #1A74FF 22%, #202020);
  --blue-border: color-mix(in srgb, #3AA5F0 34%, #5c5c5c);
  --red: #FF5E5E;
  --red-bg: color-mix(in srgb, #F04142 24%, #202020);
  --red-border: color-mix(in srgb, #FF5E5E 34%, #5c5c5c);
  --amber: #FFC740;
  --amber-bg: color-mix(in srgb, #FFBA12 22%, #202020);
  --purple: #a78bfa;
  --purple-bg: color-mix(in srgb, #7a5af8 22%, #202020);

  --shadow-xs: 0 1px 0 rgba(0, 0, 0, 0.2);
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3), 0 1px 3px rgba(0, 0, 0, 0.2);
  --shadow-md: 0 6px 24px rgba(0, 0, 0, 0.4), 0 2px 6px rgba(0, 0, 0, 0.25);
  --shadow-lg: 0 24px 60px rgba(0, 0, 0, 0.6), 0 8px 16px rgba(0, 0, 0, 0.3);
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html, body { height: 100%; }
body {
  font-family: var(--sans);
  font-size: 14px;
  line-height: 1.7;
  color: var(--text);
  background: var(--bg-app);
  -webkit-font-smoothing: antialiased;
}
button { font-family: inherit; cursor: pointer; border: none; background: none; color: inherit; font-size: inherit; }
input, select, textarea { font-family: inherit; font-size: inherit; color: var(--text-strong); }

#app { display: flex; height: 100vh; }

/* ---------------- 侧边导航 ---------------- */
.nav-rail {
  width: var(--nav-w);
  flex-shrink: 0;
  background: var(--bg-panel);
  border-right: 1px solid var(--border-soft);
  display: flex;
  flex-direction: column;
  padding: 16px 10px;
  gap: 4px;
}
.nav-logo {
  display: flex; align-items: center; gap: 10px;
  padding: 6px 10px 18px;
}
.nav-logo-mark {
  width: 34px; height: 34px; border-radius: var(--radius);
  background: var(--accent); color: var(--accent-contrast);
  display: grid; place-items: center;
  font-size: 18px; font-weight: 700;
}
.nav-logo-text { font-weight: 700; font-size: 15px; color: var(--text-strong); }
.nav-list { display: flex; flex-direction: column; gap: 2px; flex: 1; }
.nav-item {
  display: flex; align-items: center; gap: 10px;
  padding: 8px 10px; border-radius: var(--radius);
  color: var(--text-muted); font-weight: 500;
  transition: background var(--dur-quick) var(--ease-out), color var(--dur-quick) var(--ease-out);
  text-align: left;
}
.nav-item:hover { background: var(--bg-fill-tertiary); color: var(--text-strong); }
.nav-item.active { background: var(--accent-soft); color: var(--text-strong); font-weight: 600; }
.nav-ico { width: 20px; text-align: center; font-size: 15px; }
.nav-foot { padding: 8px 6px 0; border-top: 1px solid var(--border-soft); display: flex; }
.icon-btn {
  width: 32px; height: 32px; border-radius: var(--radius);
  display: grid; place-items: center; font-size: 15px; color: var(--text-muted);
  transition: background var(--dur-quick);
}
.icon-btn:hover { background: var(--bg-fill-secondary); }

/* ---------------- 主区域 ---------------- */
.main {
  flex: 1; overflow-y: auto;
  padding: 28px 36px 80px;
  scroll-behavior: smooth;
}
.main-inner { max-width: 880px; margin: 0 auto; }
.page-title { font-size: 24px; font-weight: 700; color: var(--text-strong); margin-bottom: 4px; }
.page-sub { color: var(--text-soft); margin-bottom: 24px; font-size: 13px; }

/* 卡片 */
.card {
  background: var(--bg);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-lg);
  padding: 18px 20px;
  box-shadow: var(--shadow-xs);
  transition: box-shadow var(--dur-enter) var(--ease-out), border-color var(--dur-enter) var(--ease-out);
}
.card:hover { box-shadow: var(--shadow-sm); }
.card.clickable { cursor: pointer; }
.card.clickable:hover { border-color: var(--border-strong); box-shadow: var(--shadow-md); }

/* 网格 */
.grid { display: grid; gap: 12px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 1100px) { .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); } }

/* 徽标/药丸 */
.pill {
  display: inline-flex; align-items: center; gap: 4px;
  font-size: 12px; font-weight: 500;
  padding: 2px 9px; border-radius: var(--radius-pill);
  border: 1px solid var(--border);
  color: var(--text-muted); background: var(--bg);
  white-space: nowrap;
}
.pill.brand { background: var(--brand-soft); border-color: var(--brand-weak); color: var(--brand-text); }
.pill.blue { background: var(--blue-bg); border-color: var(--blue-border); color: var(--blue); }
.pill.green { background: var(--green-bg); border-color: var(--green-border); color: var(--green); }
.pill.red { background: var(--red-bg); border-color: var(--red-border); color: var(--red); }
.pill.amber { background: var(--amber-bg); border-color: var(--border); color: var(--amber); }
.pill.purple { background: var(--purple-bg); border-color: var(--border); color: var(--purple); }

/* 按钮 */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  padding: 8px 16px; border-radius: var(--radius);
  font-weight: 600; font-size: 13.5px;
  border: 1px solid transparent;
  transition: all var(--dur-quick) var(--ease-out);
}
.btn.primary { background: var(--accent); color: var(--accent-contrast); }
.btn.primary:hover { background: var(--text-strong); }
.btn.ghost { border-color: var(--border); color: var(--text); background: var(--bg); }
.btn.ghost:hover { background: var(--bg-fill-tertiary); }
.btn.brand { background: var(--brand); color: #1c3a05; }
.btn.brand:hover { filter: brightness(1.05); }
.btn.danger { background: var(--red-bg); color: var(--red); border-color: var(--red-border); }
.btn.sm { padding: 4px 10px; font-size: 12.5px; font-weight: 500; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }

/* 表单 */
.field { display: flex; flex-direction: column; gap: 5px; margin-bottom: 14px; }
.field label { font-size: 12.5px; font-weight: 600; color: var(--text-muted); }
.input, .select, .textarea {
  width: 100%; padding: 8px 12px;
  border: 1px solid var(--border); border-radius: var(--radius);
  background: var(--bg); color: var(--text-strong);
  outline: none;
  transition: border-color var(--dur-quick), box-shadow var(--dur-quick), background var(--dur-quick);
}
.input:focus, .select:focus, .textarea:focus {
  border-color: var(--border-strong);
  box-shadow: 0 0 0 3px var(--bg-fill-secondary);
}
.input:hover, .textarea:hover { border-color: var(--border-strong); }
.textarea { resize: vertical; min-height: 70px; }

/* 下拉框：自绘弹层，替换系统原生蓝色高亮列表 */
.select {
  appearance: none; -webkit-appearance: none;
  padding-right: 34px;
  background-image:
    linear-gradient(45deg, transparent 50%, var(--text-soft) 25%),
    linear-gradient(135deg, var(--text-soft) 25%, transparent 50%);
  background-position:
    calc(100% - 18px) calc(50% - 1px),
    calc(100% - 13px) calc(50% - 1px);
  background-size: 5px 5px, 5px 5px;
  background-repeat: no-repeat;
  cursor: pointer;
  font-weight: 500;
  user-select: none;
}
.select:hover { border-color: var(--border-strong); background-color: var(--bg-fill-tertiary); }
.select:focus { border-color: var(--brand-weak); background-color: var(--bg); box-shadow: 0 0 0 3px var(--brand-soft); }
.select:disabled { opacity: 0.5; cursor: not-allowed; }
/* 原生弹层兜底（组件未接管时） */
.select option { background: var(--bg-panel); color: var(--text-strong); font-weight: 400; }

.select.clickjump { color: var(--text-strong); } /* 防止自绘弹层触发时文字闪蓝 */

/* 自绘下拉弹层 */
.ui-select-pop {
  position: fixed; z-index: 90;
  min-width: 120px; max-height: 288px; overflow-y: auto;
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-md);
  padding: 4px;
  opacity: 0; transform: translateY(-4px) scale(0.99);
  transition: opacity var(--dur-quick) var(--ease-out), transform var(--dur-quick) var(--ease-out);
}
.ui-select-pop.open { opacity: 1; transform: translateY(0) scale(1); }
.ui-select-pop .ui-opt {
  display: flex; align-items: center; gap: 8px;
  padding: 7px 10px; border-radius: var(--radius-sm);
  font-size: 13.5px; color: var(--text-strong);
  cursor: pointer; line-height: 1.5;
  transition: background var(--dur-quick);
}
.ui-select-pop .ui-opt:hover { background: var(--bg-fill-tertiary); }
.ui-select-pop .ui-opt.active {
  background: var(--brand-soft); color: var(--brand-text); font-weight: 600;
}
.ui-select-pop .ui-opt.active::after {
  content: "✓"; margin-left: auto; font-size: 12px; font-weight: 700;
}

/* ---------------- 首页 ---------------- */
.hero {
  padding: 30px 30px 26px;
  border-radius: var(--radius-lg);
  background: var(--bg-panel);
  border: 1px solid var(--border-soft);
  margin-bottom: 20px;
}
.hero h1 { font-size: 26px; color: var(--text-strong); margin-bottom: 6px; }
.hero p { color: var(--text-muted); max-width: 560px; }
.hero-stats { display: flex; gap: 26px; margin-top: 18px; flex-wrap: wrap; }
.hstat { display: flex; flex-direction: column; }
.hstat b { font-size: 22px; color: var(--text-strong); font-weight: 700; }
.hstat span { font-size: 12px; color: var(--text-soft); }

.sec-title { display: flex; align-items: baseline; justify-content: space-between; margin: 26px 0 12px; }
.sec-title h2 { font-size: 17px; color: var(--text-strong); }
.sec-title a, .sec-title .link { font-size: 12.5px; color: var(--text-soft); cursor: pointer; }
.sec-title .link:hover { color: var(--text-strong); }

/* 年份卡 */
.year-card { display: flex; flex-direction: column; gap: 8px; }
.year-card .yc-head { display: flex; justify-content: space-between; align-items: center; }
.year-card .yc-year { font-size: 17px; font-weight: 700; color: var(--text-strong); }
.year-card .yc-meta { display: flex; gap: 6px; flex-wrap: wrap; }

/* 知识点卡 */
.kp-card { display: flex; flex-direction: column; gap: 6px; position: relative; overflow: hidden; }
.kp-card .kp-name { font-weight: 600; color: var(--text-strong); }
.kp-card .kp-meta { display: flex; justify-content: space-between; align-items: center; }
.kp-learn { font-size: 12px; color: var(--text-soft); display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }

/* 进度条 */
.bar { height: 6px; border-radius: var(--radius-pill); background: var(--bg-subtle); overflow: hidden; }
.bar > i { display: block; height: 100%; border-radius: var(--radius-pill); background: var(--brand); transition: width var(--dur-enter) var(--ease-out); }
.bar.red > i { background: var(--red); }

/* ---------------- 答题界面 ---------------- */
.quiz-topbar {
  position: sticky; top: -28px; z-index: 20;
  margin: -28px -36px 18px; padding: 14px 36px;
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border-soft);
  display: flex; align-items: center; gap: 12px;
}
.quiz-topbar .qt-title { font-weight: 700; color: var(--text-strong); flex: 1; }
.quiz-progress { font-size: 12.5px; color: var(--text-soft); font-variant-numeric: tabular-nums; }

.quiz-card { max-width: 780px; margin: 0 auto; }
.q-stem {
  font-size: 15.5px; color: var(--text-strong); line-height: 1.9;
  padding: 4px 0 14px;
}
.q-options { display: flex; flex-direction: column; gap: 8px; }
.q-opt {
  display: flex; gap: 10px; align-items: flex-start;
  padding: 10px 14px; border-radius: var(--radius);
  border: 1px solid var(--border-soft);
  cursor: pointer; transition: all var(--dur-quick) var(--ease-out);
  line-height: 1.8;
}
.q-opt:hover { background: var(--bg-fill-tertiary); }
.q-opt .opt-key {
  width: 24px; height: 24px; flex-shrink: 0; border-radius: var(--radius-pill);
  border: 1px solid var(--border); display: grid; place-items: center;
  font-size: 12px; font-weight: 700; color: var(--text-muted); margin-top: 2px;
}
.q-opt.selected { border-color: var(--border-strong); background: var(--bg-fill-tertiary); }
.q-opt.selected .opt-key { background: var(--accent); color: var(--accent-contrast); border-color: var(--accent); }
.q-opt.correct { border-color: var(--green-border); background: var(--green-bg); }
.q-opt.correct .opt-key { background: var(--green); border-color: var(--green); color: #fff; }
.q-opt.wrong { border-color: var(--red-border); background: var(--red-bg); }
.q-opt.wrong .opt-key { background: var(--red); border-color: var(--red); color: #fff; }
.q-opt.disabled { pointer-events: none; }

.q-actions { display: flex; gap: 10px; margin-top: 18px; align-items: center; flex-wrap: wrap; }
.q-feedback { margin-top: 14px; padding: 12px 14px; border-radius: var(--radius); font-size: 13.5px; }
.q-feedback.ok { background: var(--green-bg); color: var(--brand-text); border: 1px solid var(--green-border); }
.q-feedback.no { background: var(--red-bg); color: var(--red); border: 1px solid var(--red-border); }

.answer-block {
  margin-top: 14px; border-radius: var(--radius);
  border: 1px solid var(--border-soft);
  overflow: hidden;
}
.answer-block .ab-head {
  display: flex; align-items: center; gap: 8px;
  padding: 9px 14px; background: var(--bg-panel);
  font-size: 13px; font-weight: 600; color: var(--text-muted);
  cursor: pointer; user-select: none;
}
.answer-block .ab-body { padding: 14px 16px; font-size: 14px; color: var(--text); line-height: 1.9; border-top: 1px solid var(--border-soft); }

/* 解答过程 markdown */
.prose { line-height: 1.9; }
.prose p { margin: 6px 0; }
.prose .katex-display { margin: 10px 0; overflow-x: auto; overflow-y: hidden; padding: 2px 0; }

/* 做题布局：左题右导航 */
.quiz-layout { display: grid; grid-template-columns: 1fr 200px; gap: 22px; align-items: start; }
@media (max-width: 1000px) { .quiz-layout { grid-template-columns: 1fr; } }
.q-nav-panel {
  position: sticky; top: 60px;
  display: flex; flex-direction: column; gap: 10px;
  padding: 14px; border: 1px solid var(--border-soft); border-radius: var(--radius-lg);
  background: var(--bg-panel);
}
.q-nav-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 5px; }
.q-nav-cell {
  aspect-ratio: 1; border-radius: var(--radius-sm);
  border: 1px solid var(--border-soft);
  font-size: 11.5px; display: grid; place-items: center;
  color: var(--text-muted); font-variant-numeric: tabular-nums;
  transition: all var(--dur-quick);
}
.q-nav-cell:hover { border-color: var(--border-strong); }
.q-nav-cell.cur { background: var(--accent); color: var(--accent-contrast); border-color: var(--accent); }
.q-nav-cell.done-ok { background: var(--green-bg); border-color: var(--green-border); color: var(--green); }
.q-nav-cell.done-no { background: var(--red-bg); border-color: var(--red-border); color: var(--red); }

/* ---------------- 搜索 ---------------- */
.search-bar { display: flex; gap: 10px; margin-bottom: 18px; }
.search-bar .input { flex: 1; }
.search-hit { margin-bottom: 10px; }
.search-hit .sh-stem { font-size: 13.5px; color: var(--text); display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.search-hit .sh-meta { display: flex; gap: 6px; margin-bottom: 6px; flex-wrap: wrap; }

/* ---------------- 错题本 ---------------- */
.wrong-stat-row { display: flex; gap: 12px; margin-bottom: 20px; flex-wrap: wrap; }
.wstat {
  flex: 1; min-width: 140px;
  padding: 14px 16px; border-radius: var(--radius-lg);
  border: 1px solid var(--border-soft); background: var(--bg);
}
.wstat b { font-size: 22px; color: var(--text-strong); }
.wstat span { display: block; font-size: 12px; color: var(--text-soft); }
.weak-row { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; }
.weak-row .wr-name { width: 150px; font-size: 13px; color: var(--text-strong); text-align: right; flex-shrink: 0; }
.weak-row .bar { flex: 1; }
.weak-row .wr-n { width: 70px; font-size: 12px; color: var(--text-soft); flex-shrink: 0; }

/* ---------------- 设置页 ---------------- */
.provider-card { margin-bottom: 12px; }
.provider-card .pc-head { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; }
.provider-card .pc-head b { flex: 1; }

/* ---------------- AI 面板 ---------------- */
.ai-chat { display: flex; flex-direction: column; gap: 12px; max-width: 780px; }
.ai-msg { padding: 12px 15px; border-radius: var(--radius-lg); max-width: 92%; font-size: 14px; line-height: 1.85; }
.ai-msg.user { align-self: flex-end; background: var(--accent); color: var(--accent-contrast); }
.ai-msg.assistant { align-self: flex-start; background: var(--bg-panel); border: 1px solid var(--border-soft); }
.ai-msg .reasoning { font-size: 12px; color: var(--text-soft); border-left: 2px solid var(--border); padding-left: 10px; margin-bottom: 8px; white-space: pre-wrap; }

/* 生成题卡 */
.gen-q { margin-bottom: 14px; }

/* 空状态 */
.empty {
  text-align: center; padding: 60px 20px; color: var(--text-faint);
}
.empty .e-ico { font-size: 40px; margin-bottom: 10px; }

/* toast */
#toast {
  position: fixed; bottom: 30px; left: 50%; transform: translateX(-50%) translateY(20px);
  background: var(--accent); color: var(--accent-contrast);
  padding: 9px 18px; border-radius: var(--radius-pill); font-size: 13px;
  opacity: 0; pointer-events: none; transition: all var(--dur-enter) var(--ease-out);
  z-index: 100; box-shadow: var(--shadow-md);
}
#toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* KaTeX 尺寸微调 */
.katex { font-size: 1.05em; }