:root {
  --ink: #2b2a27;
  --paper: #f7f3ea;
  --paper-2: #fffdf8;
  --line: #e7ded0;
  --red: #c0392b;       /* 涨/强调：中国红 */
  --red-deep: #9b1c1c;
  --green: #2e8b57;     /* 跌/分区 */
  --blue: #2f6f9f;
  --gold: #c9a227;
  --shadow: 0 10px 30px rgba(0,0,0,.08);
  --radius: 16px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", system-ui, sans-serif;
  color: var(--ink);
  background: linear-gradient(160deg, #faf6ee 0%, #f2ece0 100%);
  min-height: 100vh;
}

.hidden { display: none !important; }

/* ===== 顶部导航 ===== */
.nav {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,253,248,.82);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.nav-inner {
  max-width: 1080px; margin: 0 auto; padding: 14px 22px;
  display: flex; align-items: center; gap: 26px;
}
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--ink); }
.brand-mark {
  width: 38px; height: 38px; border-radius: 10px;
  background: linear-gradient(135deg, var(--red), var(--red-deep));
  color: #fff; display: grid; place-items: center; font-weight: 700; font-size: 20px;
  box-shadow: 0 6px 16px rgba(192,57,43,.3);
}
.brand-text { font-size: 19px; font-weight: 700; letter-spacing: 2px; }
.nav-links { display: flex; gap: 22px; margin-left: 12px; }
.nav-links a { color: var(--ink); text-decoration: none; opacity: .8; font-size: 15px; }
.nav-links a:hover { color: var(--red); opacity: 1; }
.nav-right { margin-left: auto; display: flex; align-items: center; gap: 12px; }
.who { font-size: 14px; opacity: .85; }

.btn-ghost {
  border: 1px solid var(--red); color: var(--red); background: transparent;
  padding: 8px 18px; border-radius: 999px; cursor: pointer; font-size: 14px; font-weight: 600;
}
.btn-ghost:hover { background: var(--red); color: #fff; }

/* ===== Hero ===== */
.hero { position: relative; overflow: hidden; padding: 80px 22px 60px; text-align: center; }
.hero-glow {
  position: absolute; inset: -40% 0 auto 0; height: 420px;
  background: radial-gradient(circle at 50% 0, rgba(192,57,43,.14), transparent 60%);
  pointer-events: none;
}
.hero-content { position: relative; max-width: 760px; margin: 0 auto; }
.badge {
  display: inline-block; padding: 6px 16px; border-radius: 999px;
  background: rgba(201,162,39,.14); color: var(--gold); font-size: 13px; font-weight: 600; margin-bottom: 18px;
}
.hero h1 {
  font-size: 46px; line-height: 1.2; margin: 0 0 18px; font-weight: 800;
  letter-spacing: 1px;
}
.hero-sub { font-size: 17px; opacity: .78; line-height: 1.7; margin-bottom: 30px; }
.hero-cta { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }
.btn-primary {
  background: linear-gradient(135deg, var(--red), var(--red-deep)); color: #fff; border: none;
  padding: 13px 30px; border-radius: 999px; font-size: 16px; font-weight: 700; cursor: pointer;
  text-decoration: none; box-shadow: 0 10px 24px rgba(192,57,43,.3); transition: transform .15s;
}
.btn-primary:hover { transform: translateY(-2px); }
.btn-outline {
  background: #fff; color: var(--ink); border: 1px solid var(--line);
  padding: 13px 30px; border-radius:  999px; font-size: 16px; font-weight: 600; cursor: pointer; text-decoration: none;
}
.btn-outline:hover { border-color: var(--red); color: var(--red); }

.hero-stats { display: flex; gap: 40px; justify-content: center; margin-top: 46px; }
.hero-stats div { text-align: center; }
.hero-stats b { display: block; font-size: 32px; color: var(--red-deep); font-weight: 800; }
.hero-stats span { font-size: 13px; opacity: .65; }

/* ===== Section ===== */
.section { max-width: 1080px; margin: 0 auto; padding: 70px 22px; }
.section.alt { background: rgba(255,255,255,.5); }
.section-head { text-align: center; margin-bottom: 36px; }
.section-head h2 { font-size: 28px; margin: 0 0 8px; }
.section-head p { opacity: .7; margin: 0; }

/* ===== 筛选 chips ===== */
.filter-bar { display: flex; gap: 10px; justify-content: center; margin-bottom: 26px; flex-wrap: wrap; }
.chip {
  border: 1px solid var(--line); background: #fff; color: var(--ink);
  padding: 8px 20px; border-radius: 999px; cursor: pointer; font-size: 14px; transition: all .15s;
}
.chip:hover { border-color: var(--red); }
.chip.active { background: var(--red); color: #fff; border-color: var(--red); }

/* ===== 时间轴 ===== */
.timeline { position: relative; max-width: 860px; margin: 0 auto; padding-left: 26px; }
.timeline::before {
  content: ""; position: absolute; left: 8px; top: 8px; bottom: 8px; width: 3px;
  background: linear-gradient(var(--red), var(--blue), var(--green)); border-radius: 3px;
}
.tl-item { position: relative; margin-bottom: 20px; }
.tl-dot {
  position: absolute; left: -23px; top: 14px; width: 14px; height: 14px; border-radius: 50%;
  background: #fff; border: 3px solid var(--gold); box-shadow: 0 0 0 4px rgba(201,162,39,.15);
}
.tl-item.古代史 .tl-dot { border-color: var(--green); box-shadow: 0 0 0 4px rgba(46,139,87,.15); }
.tl-item.近代史 .tl-dot { border-color: var(--red); box-shadow: 0  0 0 4px rgba(192,57,43,.15); }
.tl-item.现代史 .tl-dot { border-color: var(--blue); box-shadow: 0 0 0 4px rgba(47,111,159,.15); }
.tl-card {
  background: var(--paper-2); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 18px 20px; box-shadow: var(--shadow); transition: transform .15s;
}
.tl-card:hover { transform: translateX(4px); }
.tl-head { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-bottom: 8px; }
.tl-dynasty { font-weight: 700; font-size: 17px; }
.tl-era { font-size: 12px; padding: 3px 10px; border-radius: 999px; background: rgba(0,0,0,.05); }
.tl-era.古代史 { background: rgba(46,139,87,.14); color: var(--green); }
.tl-era.近代史 { background: rgba(192,57,43,.14); color: var(--red); }
.tl-era.现代史 { background: rgba(47,111,159,.14); color: var(--blue); }
.tl-date { font-size: 13px; opacity: .6; margin-left: auto; }
.tl-summary { margin: 0 0 10px; line-height: 1.6; }
.tl-events { display: flex; flex-wrap: wrap; gap: 8px; }
.tl-event {
  font-size: 13px; background: rgba(201,162,39,.12); color: #8a6d1f;
  padding: 4px 10px; border-radius: 8px;
}

/* ===== 题库预览 ===== */
.quiz-preview { max-width: 860px; margin: 0 auto; }
.quiz-meta-row { display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 18px; }
.pill { font-size: 13px; background: var(--paper-2); border: 1px solid var(--line); padding: 6px 14px; border-radius: 999px; }
.quiz-sample { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.q-mini { background: var(--paper-2); border: 1px solid var(--line); border-radius: 14px; padding: 16px; }
.qm-tag { display: inline-block; font-size: 12px; color: var(--red); font-weight: 600; margin-bottom: 6px; }
.qm-text { line-height: 1.5; }
.quiz-cta { text-align: center; margin-top: 26px; }

/* ===== 应用区 ===== */
.app { max-width: 1080px; margin: 0 auto; padding: 26px 22px 60px; }
.app-tabs { display: flex; gap: 10px; margin-bottom: 24px; }
.tab {
  border: 1px solid var(--line); background: #fff; color: var(--ink);
  padding: 10px 22px; border-radius: 12px; cursor: pointer; font-size: 15px; font-weight: 600;
}
.tab.active { background: var(--red); color: #fff; border-color: var(--red); }

.quiz-controls { display: flex; align-items: center; gap: 16px; margin-bottom: 20px; flex-wrap: wrap; }
.quiz-controls select { padding: 8px 12px; border-radius: 10px; border: 1px solid var(--line); font-size: 14px; }
.btn-outline.sm { padding: 8px 18px; font-size: 14px; }
.score { margin-left: auto; font-weight: 700; color: var(--red-deep); }

.quiz-card {
  background: var(--paper-2); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 26px; box-shadow: var(--shadow); max-width: 720px;
}
.q-meta { font-size: 13px; color: var(--red); font-weight: 600; margin-bottom: 12px; }
.q-text { font-size: 19px; line-height: 1.6; margin-bottom: 20px; }
.q-options { display: grid; gap: 12px; }
.q-opt {
  text-align: left; padding: 14px 18px; border: 1px solid var(--line); border-radius: 12px;
  background: #fff; cursor: pointer; font-size: 15px; transition: all .15s;
}
.q-opt:hover:not(:disabled) { border-color: var(--red); background: rgba(192,57,43,.04); }
.q-opt.correct { background: rgba(192,57,43,.15); border-color: var(--red); color: var(--red-deep); font-weight: 700; }
.q-opt.wrong { background: rgba(46,139,87,.15); border-color: var(--green); }
.q-feedback { margin-top: 18px; }
.tag-ok { color: var(--red); font-weight: 700; }
.tag-bad { color: var(--green); font-weight: 700; }
.q-explain { margin-top: 8px; opacity: .8; line-height: 1.6; }

/* ===== 进度 ===== */
.stat-grid { display: grid; grid-template-columns: repeat(4,1fr); gap: 16px; margin-bottom: 28px; }
.stat-box { background: var(--paper-2); border: 1px solid var(--line); border-radius: var(--radius); padding: 22px; text-align: center; box-shadow: var(--shadow); }
.stat-box .num { font-size: 30px; font-weight: 800; color: var(--red-deep); }
.stat-box .lbl { font-size: 13px; opacity: .7; margin-top: 6px; }
.section-title { font-size: 18px; font-weight: 700; margin: 0 0 14px; }
.wrong-item { background: var(--paper-2); border: 1px solid var(--line); border-radius: 12px; padding: 16px; margin-bottom: 12px; }
.wq { font-weight: 600; margin-bottom: 6px; }
.wa { color: var(--red-deep); margin-bottom: 4px; }
.we { opacity: .8; font-size: 14px; }

/* ===== Modal ===== */
.modal-mask {
  position: fixed; inset: 0; background: rgba(43,42,39,.5); backdrop-filter: blur(4px);
  display: grid; place-items: center; z-index: 100;
}
.modal {
  background: var(--paper-2); width: 380px; max-width: 90vw; border-radius: 20px;
  padding: 32px; position: relative; box-shadow: 0 30px 60px rgba(0,0,0,.25);
}
.modal-close { position: absolute; top: 16px; right: 18px; background: none; border: none; font-size: 20px; cursor: pointer; opacity: .5; }
.modal-close:hover { opacity: 1; }
.modal h2 { margin: 0 0  6px; font-size: 24px; }
.modal-sub { opacity: .7; margin: 0 0 18px; font-size: 14px; }
.row { margin-bottom: 14px; }
.row label { display: block; font-size: 13px; margin-bottom: 6px; opacity: .8; }
.row input {
  width: 100%; padding: 12px 14px; border: 1px solid var(--line); border-radius: 10px; font-size: 15px;
  background: #fff;
}
.row input:focus { outline: none; border-color: var(--red); }
.btn-primary.block { width: 100%; margin-top: 6px; }
.auth-msg { font-size: 13px; margin-bottom: 10px; min-height: 18px; }
.auth-msg.err { color: var(--green); }
.auth-switch { text-align: center; margin-top: 14px; font-size: 14px; }
.auth-switch a { color: var(--red); cursor: pointer; font-weight: 600; }

.empty { text-align: center; opacity: .6; padding: 30px; }
.loading { text-align: center; opacity: .6; padding: 30px; }

/* ===== Footer ===== */
.foot {
  max-width: 1080px; margin: 0 auto; padding: 40px 22px; text-align: center;
  border-top: 1px solid var(--line); display: flex; flex-direction: column; gap: 6px;
}
.foot-sub { font-size: 12px; opacity: .5; }

@media (max-width: 640px) {
  .hero h1 { font-size: 32px; }
  .hero-stats { gap: 24px; }
  .quiz-sample { grid-template-columns: 1fr; }
  .stat-grid { grid-template-columns: repeat(2,1fr); }
  .nav-links { display: none; }
}