/* ============================================================
   汇易驾考 · 科目四  —— 主样式表
   设计基调：夜间高速仪表盘 + 车道流光
   ============================================================ */

:root {
  --bg: #0b0f19;
  --bg-elev: #121826;
  --bg-elev-2: #1a2233;
  --bg-elev-3: #212b40;
  --line-amber: #ffc53d;
  --signal-green: #00d68f;
  --signal-red: #ff4757;
  --signal-blue: #4da8ff;
  --text: #f5f7fa;
  --text-dim: #94a3b8;
  --text-faint: #5b6478;
  --border: rgba(255, 255, 255, 0.08);
  --border-strong: rgba(255, 255, 255, 0.16);
  --radius-sm: 10px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --font-display: "Source Han Serif SC", "Noto Serif SC", "Songti SC", "STSong", "SimSun", serif;
  --font-body: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Consolas, monospace;
  --shadow-glow-amber: 0 0 40px rgba(255, 197, 61, 0.18);
  --shadow-glow-green: 0 0 40px rgba(0, 214, 143, 0.22);
  --shadow-glow-red: 0 0 40px rgba(255, 71, 87, 0.22);
  --ease-flow: cubic-bezier(0.65, 0, 0.35, 1);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: 0.001ms !important; animation-iteration-count: 1 !important; transition-duration: 0.001ms !important; }
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  line-height: 1.7;
  overflow-x: hidden;
  position: relative;
}

a { color: inherit; text-decoration: none; }
ul { list-style: none; margin: 0; padding: 0; }
button { font-family: inherit; cursor: pointer; }
img { max-width: 100%; display: block; }

::selection { background: var(--line-amber); color: #0b0f19; }

/* -------------------- 背景大气层：极光 + 车道流光 -------------------- */
.bg-aurora {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  overflow: hidden;
}
.bg-aurora::before,
.bg-aurora::after {
  content: "";
  position: absolute;
  width: 60vw;
  height: 60vw;
  border-radius: 50%;
  filter: blur(120px);
  opacity: 0.28;
  animation: aurora-float 22s var(--ease-flow) infinite alternate;
}
.bg-aurora::before {
  background: radial-gradient(circle, var(--signal-blue), transparent 70%);
  top: -20vw;
  left: -10vw;
}
.bg-aurora::after {
  background: radial-gradient(circle, var(--line-amber), transparent 70%);
  bottom: -25vw;
  right: -15vw;
  animation-delay: -11s;
}
@keyframes aurora-float {
  0%   { transform: translate(0, 0) scale(1); }
  50%  { transform: translate(6vw, 8vw) scale(1.15); }
  100% { transform: translate(-4vw, -6vw) scale(0.95); }
}

#particle-canvas {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: 0.55;
}

.page-shell { position: relative; z-index: 1; min-height: 100vh; display: flex; flex-direction: column; }

/* -------------------- 车道虚线流动分隔线（签名元素） -------------------- */
.lane-divider {
  height: 4px;
  width: 100%;
  background-image: repeating-linear-gradient(
    90deg,
    var(--line-amber) 0px,
    var(--line-amber) 40px,
    transparent 40px,
    transparent 76px
  );
  background-size: 76px 4px;
  animation: lane-flow 1.4s linear infinite;
  opacity: 0.85;
  box-shadow: 0 0 16px rgba(255, 197, 61, 0.55);
}
@keyframes lane-flow {
  from { background-position-x: 0; }
  to   { background-position-x: -76px; }
}

/* -------------------- 顶部导航 -------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(16px) saturate(140%);
  background: rgba(11, 15, 25, 0.72);
  border-bottom: 1px solid var(--border);
}
.nav-wrap {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 24px;
  height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: relative;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-size: 21px;
  font-weight: 700;
  letter-spacing: 1px;
}
.brand .dot {
  width: 10px; height: 10px; border-radius: 50%;
  background: var(--signal-green);
  box-shadow: 0 0 12px var(--signal-green);
  animation: pulse-dot 2s ease-in-out infinite;
}
.brand small {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--text-dim);
  font-weight: 400;
  letter-spacing: 2px;
  margin-left: 4px;
}
@keyframes pulse-dot {
  0%, 100% { transform: scale(1); opacity: 1; }
  50% { transform: scale(1.4); opacity: 0.6; }
}
.nav-links { display: flex; align-items: center; gap: 6px; }
.nav-links a {
  padding: 9px 16px;
  border-radius: 999px;
  font-size: 14.5px;
  color: var(--text-dim);
  transition: color .25s, background .25s;
  position: relative;
}
.nav-links a:hover, .nav-links a.active { color: var(--text); background: var(--bg-elev-2); }
.nav-auth { display: flex; align-items: center; gap: 10px; }
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: 999px;
  border: 1px solid var(--border-strong);
  background: var(--bg-elev-2);
  color: var(--text);
  font-size: 14.5px;
  font-weight: 500;
  transition: transform .25s var(--ease-flow), box-shadow .25s, background .25s, border-color .25s;
}
.btn:hover { transform: translateY(-2px); border-color: var(--line-amber); box-shadow: var(--shadow-glow-amber); }
.btn:active { transform: translateY(0); }
.btn-primary {
  background: linear-gradient(135deg, var(--line-amber), #ff9f4d);
  color: #1a1200;
  border: none;
  font-weight: 700;
}
.btn-primary:hover { box-shadow: 0 8px 30px rgba(255, 197, 61, 0.35); }
.btn-ghost { background: transparent; border-color: var(--border); color: var(--text-dim); }
.btn-ghost:hover { color: var(--text); }
.btn-sm { padding: 7px 14px; font-size: 13px; }
.user-chip {
  display: flex; align-items: center; gap: 8px;
  padding: 6px 14px 6px 6px;
  border-radius: 999px;
  background: var(--bg-elev-2);
  border: 1px solid var(--border);
  font-size: 14px;
}
.user-chip .avatar {
  width: 26px; height: 26px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-family: var(--font-mono); font-weight: 700; font-size: 12px;
  color: #0b0f19;
}

/* 移动端导航 */
.nav-toggle { display: none; background: none; border: none; color: var(--text); font-size: 22px; }
@media (max-width: 900px) {
  .nav-links { display: none; }
  .nav-toggle { display: block; }
  .nav-wrap.open .nav-links {
    display: flex; position: absolute; top: 72px; left: 0; right: 0;
    flex-direction: column; background: var(--bg-elev); padding: 12px; border-bottom: 1px solid var(--border);
    border-radius: 0 0 16px 16px;
  }
}

/* -------------------- 通用容器 / section -------------------- */
.container { max-width: 1180px; margin: 0 auto; padding: 0 24px; }
.section { padding: 88px 0; }
.section-tight { padding: 56px 0; }
.eyebrow {
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 3px;
  text-transform: uppercase;
  color: var(--line-amber);
  display: flex; align-items: center; gap: 10px;
  margin-bottom: 18px;
}
.eyebrow::before {
  content: "";
  width: 28px; height: 1px;
  background: var(--line-amber);
}
h1, h2, h3, h4 { font-family: var(--font-display); font-weight: 700; margin: 0 0 16px; }
h1 { font-size: clamp(34px, 5vw, 58px); line-height: 1.15; letter-spacing: 0.5px; }
h2 { font-size: clamp(26px, 3.4vw, 38px); line-height: 1.25; }
h3 { font-size: 20px; }
p { color: var(--text-dim); margin: 0 0 14px; }

/* -------------------- Hero -------------------- */
.hero { padding: 110px 0 60px; position: relative; }
.hero-grid { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 48px; align-items: center; }
@media (max-width: 900px) { .hero-grid { grid-template-columns: 1fr; } .hero { padding: 90px 0 40px; } }

.hero-title-line { display: block; overflow: hidden; }
.hero-title-line span {
  display: inline-block;
  transform: translateY(110%);
  animation: rise-in 0.9s var(--ease-flow) forwards;
}
.hero-title-line:nth-child(1) span { animation-delay: .05s; }
.hero-title-line:nth-child(2) span { animation-delay: .18s; color: var(--line-amber); }
@keyframes rise-in { to { transform: translateY(0); } }

.hero-desc { max-width: 480px; font-size: 16px; opacity: 0; animation: fade-up .8s var(--ease-flow) .5s forwards; }
.hero-cta { display: flex; gap: 14px; margin-top: 28px; opacity: 0; animation: fade-up .8s var(--ease-flow) .65s forwards; flex-wrap: wrap; }
@keyframes fade-up { from { opacity: 0; transform: translateY(16px); } to { opacity: 1; transform: translateY(0); } }

.hero-stats { display: flex; gap: 34px; margin-top: 44px; flex-wrap: wrap; opacity: 0; animation: fade-up .8s var(--ease-flow) .8s forwards; }
.stat .num { font-family: var(--font-mono); font-size: 32px; font-weight: 700; color: var(--text); }
.stat .num small { font-size: 15px; color: var(--line-amber); }
.stat .label { font-size: 12.5px; color: var(--text-faint); letter-spacing: 1px; margin-top: 4px; }

/* 仪表盘式 hero 视觉 */
.hero-visual { position: relative; aspect-ratio: 1 / 1; max-width: 420px; margin: 0 auto; }
.dial {
  position: absolute; inset: 0;
  border-radius: 50%;
  background: conic-gradient(from 210deg,
    var(--signal-red) 0deg, var(--line-amber) 90deg, var(--signal-green) 180deg,
    var(--bg-elev) 180deg, var(--bg-elev) 360deg);
  -webkit-mask: radial-gradient(farthest-side, transparent calc(100% - 14px), #000 calc(100% - 13px));
          mask: radial-gradient(farthest-side, transparent calc(100% - 14px), #000 calc(100% - 13px));
  animation: dial-spin 16s linear infinite;
}
@keyframes dial-spin { to { transform: rotate(360deg); } }
.dial-core {
  position: absolute; inset: 14%;
  border-radius: 50%;
  background: radial-gradient(circle at 35% 30%, var(--bg-elev-3), var(--bg-elev) 70%);
  border: 1px solid var(--border-strong);
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  box-shadow: inset 0 0 60px rgba(0,0,0,0.5), 0 0 60px rgba(255,197,61,0.12);
}
.dial-core .big { font-family: var(--font-mono); font-size: 46px; font-weight: 700; }
.dial-core .small { font-size: 12px; color: var(--text-dim); letter-spacing: 3px; margin-top: 6px; }
.dial-needle {
  position: absolute; left: 50%; top: 50%; width: 46%; height: 3px;
  background: linear-gradient(90deg, transparent, var(--signal-red));
  transform-origin: left center;
  transform: translateY(-50%) rotate(-40deg);
  animation: needle-sweep 6s ease-in-out infinite;
  border-radius: 4px;
}
@keyframes needle-sweep {
  0%, 100% { transform: translateY(-50%) rotate(-70deg); }
  50% { transform: translateY(-50%) rotate(70deg); }
}

/* -------------------- 卡片通用 -------------------- */
.card {
  background: linear-gradient(180deg, var(--bg-elev), var(--bg-elev-2));
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  position: relative;
  transition: transform .35s var(--ease-flow), border-color .35s, box-shadow .35s;
  will-change: transform;
}
.card:hover { border-color: var(--border-strong); box-shadow: 0 20px 60px rgba(0,0,0,0.35); }
.card-glow::before {
  content: "";
  position: absolute; inset: -1px;
  border-radius: inherit;
  padding: 1px;
  background: linear-gradient(135deg, var(--line-amber), transparent 40%, var(--signal-blue));
  -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  opacity: 0;
  transition: opacity .35s;
  pointer-events: none;
}
.card-glow:hover::before { opacity: 1; }

/* 三大模块入口 */
.module-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
@media (max-width: 900px) { .module-grid { grid-template-columns: 1fr; } }
.module-card { display: flex; flex-direction: column; gap: 14px; }
.module-icon {
  width: 52px; height: 52px; border-radius: 14px;
  display: flex; align-items: center; justify-content: center;
  font-size: 24px;
  background: var(--bg-elev-3);
  border: 1px solid var(--border);
}
.module-card .go {
  margin-top: auto;
  display: flex; align-items: center; gap: 8px;
  color: var(--line-amber); font-weight: 600; font-size: 14px;
  transition: gap .3s;
}
.module-card:hover .go { gap: 14px; }

/* -------------------- 技巧大全 -------------------- */
.tech-tabs { display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 32px; }
.tech-tab {
  padding: 9px 18px;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--text-dim);
  font-size: 13.5px;
  transition: all .25s;
  background: var(--bg-elev);
}
.tech-tab:hover { color: var(--text); }
.tech-tab.active { background: var(--line-amber); color: #1a1200; border-color: var(--line-amber); font-weight: 700; }

.tech-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }
@media (max-width: 800px) { .tech-grid { grid-template-columns: 1fr; } }
.tech-card { opacity: 0; transform: translateY(24px); transition: opacity .6s var(--ease-flow), transform .6s var(--ease-flow); }
.tech-card.in-view { opacity: 1; transform: translateY(0); }
.tech-card .cat { font-family: var(--font-mono); font-size: 11.5px; color: var(--signal-blue); letter-spacing: 1.5px; margin-bottom: 6px; }
.tech-card .body-text { white-space: pre-line; font-size: 14.5px; color: var(--text-dim); }
.tech-card h3 { display: flex; align-items: center; gap: 10px; }

/* -------------------- 表单（注册/登录） -------------------- */
.auth-wrap { max-width: 420px; margin: 70px auto; padding: 40px 34px; }
.field { margin-bottom: 20px; }
.field label { display: block; font-size: 13.5px; color: var(--text-dim); margin-bottom: 8px; letter-spacing: .5px; }
.field input {
  width: 100%;
  padding: 13px 16px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-strong);
  background: var(--bg);
  color: var(--text);
  font-size: 15px;
  transition: border-color .25s, box-shadow .25s;
}
.field input:focus { outline: none; border-color: var(--line-amber); box-shadow: 0 0 0 3px rgba(255, 197, 61, 0.15); }
.form-msg { padding: 12px 16px; border-radius: var(--radius-sm); font-size: 13.5px; margin-bottom: 18px; }
.form-msg.error { background: rgba(255,71,87,0.12); border: 1px solid rgba(255,71,87,0.35); color: #ff97a0; }
.form-msg.success { background: rgba(0,214,143,0.12); border: 1px solid rgba(0,214,143,0.35); color: #6fe8c3; }
.auth-switch { text-align: center; margin-top: 20px; font-size: 14px; color: var(--text-dim); }
.auth-switch a { color: var(--line-amber); font-weight: 600; }
.auth-wrap .btn-primary { width: 100%; padding: 13px; font-size: 15.5px; }

/* -------------------- 答题模块 -------------------- */
.quiz-shell { max-width: 720px; margin: 0 auto; }
.quiz-topbar { display: flex; justify-content: space-between; align-items: center; margin-bottom: 24px; flex-wrap: wrap; gap: 12px; }
.quiz-progress { font-family: var(--font-mono); font-size: 13px; color: var(--text-dim); }
.quiz-score { display: flex; gap: 18px; font-family: var(--font-mono); font-size: 13.5px; }
.quiz-score .ok { color: var(--signal-green); }
.quiz-score .bad { color: var(--signal-red); }

.question-card { padding: 34px; min-height: 260px; }
.q-type-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 11.5px;
  padding: 4px 12px;
  border-radius: 999px;
  margin-bottom: 16px;
  letter-spacing: 1px;
}
.q-type-badge.judge { background: rgba(77,168,255,0.15); color: var(--signal-blue); border: 1px solid rgba(77,168,255,0.35); }
.q-type-badge.single { background: rgba(255,197,61,0.15); color: var(--line-amber); border: 1px solid rgba(255,197,61,0.35); }
.q-type-badge.multi { background: rgba(0,214,143,0.15); color: var(--signal-green); border: 1px solid rgba(0,214,143,0.35); }
.q-content { font-size: 18px; line-height: 1.65; margin-bottom: 26px; }

.q-options { display: flex; flex-direction: column; gap: 12px; }
.q-option {
  display: flex; align-items: center; gap: 12px;
  padding: 14px 18px;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  background: var(--bg-elev-2);
  transition: border-color .2s, background .2s, transform .15s;
  font-size: 15px;
}
.q-option:hover { border-color: var(--line-amber); transform: translateX(4px); }
.q-option .tag {
  width: 28px; height: 28px; border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  background: var(--bg-elev-3);
  font-family: var(--font-mono); font-weight: 700; font-size: 13px;
  flex-shrink: 0;
}
.q-option.selected { border-color: var(--line-amber); background: rgba(255,197,61,0.08); }
.q-option.correct { border-color: var(--signal-green); background: rgba(0,214,143,0.12); box-shadow: var(--shadow-glow-green); animation: flash-correct .6s; }
.q-option.wrong { border-color: var(--signal-red); background: rgba(255,71,87,0.12); box-shadow: var(--shadow-glow-red); animation: shake .45s; }
@keyframes flash-correct { 0% { transform: scale(1); } 40% { transform: scale(1.02); } 100% { transform: scale(1); } }
@keyframes shake {
  10%, 90% { transform: translateX(-2px); }
  20%, 80% { transform: translateX(4px); }
  30%, 50%, 70% { transform: translateX(-8px); }
  40%, 60% { transform: translateX(8px); }
}

.judge-btns { display: flex; gap: 16px; }
.judge-btn {
  flex: 1;
  padding: 22px;
  text-align: center;
  font-size: 20px;
  font-weight: 700;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-strong);
  background: var(--bg-elev-2);
  transition: all .2s;
}
.judge-btn.true-btn:hover { border-color: var(--signal-green); color: var(--signal-green); }
.judge-btn.false-btn:hover { border-color: var(--signal-red); color: var(--signal-red); }
.judge-btn.correct { border-color: var(--signal-green); background: rgba(0,214,143,0.14); color: var(--signal-green); box-shadow: var(--shadow-glow-green); }
.judge-btn.wrong { border-color: var(--signal-red); background: rgba(255,71,87,0.14); color: var(--signal-red); box-shadow: var(--shadow-glow-red); }

.explanation-box {
  margin-top: 22px;
  padding: 18px 20px;
  border-radius: var(--radius-sm);
  background: var(--bg-elev-3);
  border-left: 3px solid var(--line-amber);
  font-size: 14px;
  color: var(--text-dim);
  display: none;
}
.explanation-box.show { display: block; animation: fade-up .4s var(--ease-flow); }
.explanation-box b { color: var(--text); }

.quiz-actions { display: flex; justify-content: flex-end; gap: 12px; margin-top: 24px; }

/* -------------------- 精选题库列表 -------------------- */
.bank-toolbar { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; margin-bottom: 28px; justify-content: space-between; }
.bank-filters { display: flex; gap: 10px; flex-wrap: wrap; }
.select-pill { padding: 9px 14px; border-radius: 999px; border: 1px solid var(--border-strong); background: var(--bg-elev); color: var(--text); font-size: 13.5px; }
.bank-list { display: flex; flex-direction: column; gap: 14px; }
.bank-item { padding: 22px 26px; display: flex; flex-direction: column; gap: 10px; }
.bank-item .meta { display: flex; gap: 10px; align-items: center; font-family: var(--font-mono); font-size: 11.5px; color: var(--text-faint); }
.bank-item .no { color: var(--line-amber); }
.bank-item .content { font-size: 15.5px; }
.bank-item .opts { font-size: 13.5px; color: var(--text-dim); display: grid; grid-template-columns: 1fr 1fr; gap: 6px 16px; }
.bank-item .answer-reveal { display: none; }
.bank-item .answer-reveal.show { display: block; animation: fade-up .3s; }
.bank-item .toggle-answer { align-self: flex-start; font-size: 13px; color: var(--signal-blue); background:none; border:none; padding:0; }

.pagination { display: flex; justify-content: center; gap: 8px; margin-top: 40px; flex-wrap: wrap; }
.pagination a, .pagination span {
  width: 38px; height: 38px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 10px;
  border: 1px solid var(--border);
  font-family: var(--font-mono);
  font-size: 13.5px;
  color: var(--text-dim);
}
.pagination a:hover { border-color: var(--line-amber); color: var(--text); }
.pagination .current { background: var(--line-amber); color: #1a1200; font-weight: 700; border-color: var(--line-amber); }

/* -------------------- 页脚 -------------------- */
.site-footer { margin-top: auto; border-top: 1px solid var(--border); padding: 36px 0; text-align: center; color: var(--text-faint); font-size: 13px; }

/* -------------------- 滚动揭示通用 -------------------- */
.reveal { opacity: 0; transform: translateY(28px); transition: opacity .7s var(--ease-flow), transform .7s var(--ease-flow); }
.reveal.in-view { opacity: 1; transform: translateY(0); }

/* -------------------- Toast -------------------- */
#toast-root { position: fixed; top: 90px; right: 24px; z-index: 999; display: flex; flex-direction: column; gap: 10px; }
.toast {
  padding: 14px 20px;
  border-radius: 12px;
  background: var(--bg-elev-2);
  border: 1px solid var(--border-strong);
  font-size: 14px;
  box-shadow: 0 10px 40px rgba(0,0,0,0.4);
  animation: toast-in .3s var(--ease-flow);
}
@keyframes toast-in { from { opacity: 0; transform: translateX(30px); } to { opacity: 1; transform: translateX(0); } }

/* 空状态 */
.empty-state { text-align: center; padding: 60px 20px; color: var(--text-faint); }

/* 加载动画 */
.spinner { width: 18px; height: 18px; border-radius: 50%; border: 2px solid var(--border-strong); border-top-color: var(--line-amber); animation: spin .7s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }