/* ==========================================================================
   抖音视频推广 - 全站样式
   炭黑底 + 香槟金/银白（区别于站1-8 全部配色，黑金奢华感）
   纯静态、零依赖、移动优先
   ========================================================================== */

:root {
  --bg: #101010;
  --bg-soft: #171717;
  --bg-deep: #0a0a0a;
  --panel: rgba(255, 255, 255, 0.035);
  --panel-2: rgba(255, 255, 255, 0.06);
  --edge: rgba(230, 197, 126, 0.2);
  --edge-strong: rgba(230, 197, 126, 0.45);
  --ink: #f4f1ea;
  --ink-dim: #c9c4b8;
  --ink-mute: #8f8a7d;
  --gold: #e6c57e;
  --gold-bright: #f5dfa8;
  --silver: #d9d9d9;
  --grad: linear-gradient(120deg, #b9954b 0%, #e6c57e 50%, #f5dfa8 100%);
  --radius: 18px;
  --radius-sm: 12px;
  --max: 1120px;
  --shadow: 0 24px 64px rgba(0, 0, 0, .6);
  --header-h: 66px;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  background: var(--bg);
  color: var(--ink);
  font-size: 16px;
  line-height: 1.85;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

.shell { max-width: var(--max); margin: 0 auto; padding: 0 22px; }

a { color: var(--gold); text-decoration: none; }
a:hover { color: var(--gold-bright); }

/* ---------- 顶栏 ---------- */
.topbar {
  position: sticky; top: 0; z-index: 50;
  height: var(--header-h);
  background: rgba(16, 16, 16, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--edge);
  transition: box-shadow .25s;
}
.topbar.scrolled { box-shadow: 0 10px 30px rgba(0, 0, 0, .55); }
.topbar-inner { display: flex; align-items: center; justify-content: space-between; height: 100%; }

.logo { display: inline-flex; align-items: center; gap: 10px; color: var(--ink); font-weight: 700; }
.logo-mark {
  width: 14px; height: 14px;
  transform: rotate(45deg);
  background: var(--grad);
  box-shadow: 0 0 12px rgba(230, 197, 126, .5);
}
.logo-name { font-size: 17px; letter-spacing: .5px; }

.menu { display: flex; gap: 26px; }
.menu a { color: var(--ink-dim); font-size: 14.5px; transition: color .2s; }
.menu a:hover { color: var(--gold); }

@media (max-width: 640px) {
  .menu { gap: 14px; }
  .menu a { font-size: 13px; }
}

/* ---------- 全屏 hero ---------- */
.vhero {
  min-height: 88vh;
  display: flex; align-items: center; justify-content: center;
  text-align: center;
  position: relative;
  background:
    radial-gradient(900px 480px at 50% -10%, rgba(230, 197, 126, .13), transparent 60%),
    radial-gradient(600px 300px at 85% 90%, rgba(230, 197, 126, .06), transparent 55%),
    var(--bg-deep);
  border-bottom: 1px solid var(--edge);
  padding: 90px 0 70px;
}
.vhero-inner { max-width: 820px; padding: 0 22px; }

.vhero-kicker {
  display: inline-block;
  font-size: 13px; letter-spacing: 4px;
  color: var(--gold);
  border: 1px solid var(--edge-strong);
  border-radius: 999px;
  padding: 4px 18px;
  margin-bottom: 24px;
  text-transform: uppercase;
}

.vhero h1 {
  font-size: clamp(38px, 7vw, 62px);
  line-height: 1.2;
  font-weight: 800;
  letter-spacing: 2px;
  background: var(--grad);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 22px;
}

.vhero-sub { color: var(--ink-dim); font-size: 16.5px; max-width: 640px; margin: 0 auto; }

.vhero-actions { display: flex; flex-wrap: wrap; gap: 16px; justify-content: center; margin-top: 36px; }

.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 14px 36px;
  border-radius: 4px;
  font-size: 15.5px; font-weight: 700;
  letter-spacing: 1px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform .2s, box-shadow .2s, background .2s, color .2s;
}
.btn-gold {
  background: var(--grad);
  color: #241a05;
  box-shadow: 0 12px 32px rgba(230, 197, 126, .3);
}
.btn-gold:hover { transform: translateY(-2px); color: #241a05; box-shadow: 0 16px 40px rgba(230, 197, 126, .45); }
.btn-line {
  background: transparent;
  border-color: var(--edge-strong);
  color: var(--gold);
}
.btn-line:hover { background: var(--panel); color: var(--gold-bright); }

.vhero-meta {
  display: flex; flex-wrap: wrap; justify-content: center; gap: 14px 38px;
  margin-top: 48px;
  font-size: 13.5px; color: var(--ink-mute);
}
.vhero-meta b {
  color: var(--gold);
  font-weight: 800;
  font-size: 15px;
  margin: 0 2px;
}

/* ---------- 案例页头 ---------- */
.page-head {
  padding: 72px 0 20px;
  text-align: center;
  background: var(--bg-deep);
  border-bottom: 1px solid var(--edge);
}
.page-head h1 {
  font-size: clamp(30px, 5vw, 44px);
  font-weight: 800;
  background: var(--grad);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 16px;
}

/* ---------- 区块 ---------- */
.sec { padding: 72px 0; }
.sec-alt { background: var(--bg-soft); border-top: 1px solid var(--edge); border-bottom: 1px solid var(--edge); }

.sec-title { font-size: clamp(24px, 4vw, 32px); font-weight: 800; margin-bottom: 12px; text-align: center; letter-spacing: 1px; }
.sec-lead { text-align: center; color: var(--ink-dim); max-width: 620px; margin: 0 auto 44px; }

/* ---------- 方案卡 ---------- */
.plan-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(270px, 1fr));
  gap: 22px;
}
.plan-card {
  background: var(--panel);
  border: 1px solid var(--edge);
  border-radius: var(--radius);
  padding: 30px 26px;
  position: relative;
  transition: transform .25s, border-color .25s;
}
.plan-card:hover { transform: translateY(-4px); border-color: var(--edge-strong); }
.plan-card.plan-hl { border-color: var(--edge-strong); background: var(--panel-2); }
.plan-tag {
  display: inline-block;
  font-size: 12px; letter-spacing: 2px;
  color: #241a05;
  background: var(--grad);
  border-radius: 3px;
  padding: 3px 12px;
  font-weight: 700;
  margin-bottom: 16px;
}
.plan-card h3 { font-size: 19px; margin-bottom: 10px; color: var(--ink); }
.plan-card > p { font-size: 14px; color: var(--ink-dim); margin-bottom: 18px; }
.plan-card ul { list-style: none; display: grid; gap: 9px; }
.plan-card li {
  position: relative; padding-left: 22px;
  font-size: 13.5px; color: var(--ink-mute);
}
.plan-card li::before {
  content: "◆"; position: absolute; left: 0;
  color: var(--gold); font-size: 9px; top: 4px;
}

/* ---------- 案例网格 ---------- */
.case-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px;
}
.case-card {
  background: var(--panel);
  border: 1px solid var(--edge);
  border-radius: var(--radius);
  padding: 26px 24px;
  transition: transform .25s, border-color .25s;
}
.case-card:hover { transform: translateY(-4px); border-color: var(--edge-strong); }
.case-num { margin-bottom: 14px; }
.case-num b {
  display: block;
  font-size: 34px; font-weight: 800;
  background: var(--grad);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
  line-height: 1.2;
}
.case-num span { font-size: 12.5px; color: var(--ink-mute); letter-spacing: 1px; }
.case-card h3 { font-size: 16.5px; margin-bottom: 8px; }
.case-card p { font-size: 13.5px; color: var(--ink-dim); }

.case-more { text-align: center; margin-top: 36px; }

/* ---------- 案例详情页 ---------- */
.case-detail {
  background: var(--panel);
  border: 1px solid var(--edge);
  border-radius: var(--radius);
  padding: 36px 34px;
}
.cd-head { margin-bottom: 24px; padding-bottom: 18px; border-bottom: 1px solid var(--edge); }
.cd-no {
  display: inline-block;
  font-size: 12.5px; letter-spacing: 3px;
  color: var(--gold);
  margin-bottom: 10px;
}
.cd-head h2 { font-size: clamp(20px, 3.5vw, 26px); font-weight: 800; }

.cd-block { margin-bottom: 20px; }
.cd-block h3 {
  font-size: 15px; color: var(--gold);
  letter-spacing: 1px;
  margin-bottom: 8px;
}
.cd-block p { font-size: 14.5px; color: var(--ink-dim); }

.cd-result {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 14px;
  margin: 24px 0;
  padding: 20px;
  background: var(--panel-2);
  border: 1px solid var(--edge);
  border-radius: var(--radius-sm);
}
.cd-result > div { text-align: center; }
.cd-result b {
  display: block;
  font-size: 26px; font-weight: 800;
  background: var(--grad);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
}
.cd-result span { font-size: 12.5px; color: var(--ink-mute); }

/* ---------- 答疑 ---------- */
.ask-list { max-width: 780px; margin: 0 auto; display: grid; gap: 14px; }
.ask-list details {
  background: var(--panel);
  border: 1px solid var(--edge);
  border-radius: var(--radius-sm);
  padding: 18px 22px;
  transition: border-color .2s;
}
.ask-list details[open] { border-color: var(--edge-strong); }
.ask-list summary { cursor: pointer; font-weight: 700; font-size: 16px; list-style: none; }
.ask-list summary::-webkit-details-marker { display: none; }
.ask-list summary::after { content: "+"; float: right; color: var(--gold); font-size: 20px; font-weight: 700; }
.ask-list details[open] summary::after { content: "−"; }
.ask-list details p { margin-top: 12px; color: var(--ink-dim); font-size: 14.5px; }

/* ---------- 底部 CTA ---------- */
.cta-band {
  padding: 80px 0;
  text-align: center;
  background:
    radial-gradient(700px 320px at 50% 100%, rgba(230, 197, 126, .12), transparent 65%),
    var(--bg-deep);
  border-top: 1px solid var(--edge);
}
.cta-band h2 { font-size: clamp(24px, 4vw, 32px); font-weight: 800; margin-bottom: 12px; letter-spacing: 1px; }
.cta-band p { color: var(--ink-dim); margin-bottom: 32px; }

/* ---------- 页脚 ---------- */
.foot { border-top: 1px solid var(--edge); padding: 34px 0; background: var(--bg-deep); }
.foot-inner { text-align: center; display: grid; gap: 10px; }
.foot-menu { display: flex; justify-content: center; gap: 22px; }
.foot-menu a { color: var(--ink-mute); font-size: 14px; }
.foot-menu a:hover { color: var(--gold); }
.foot-note { color: var(--ink-mute); font-size: 12.5px; }

/* ---------- 入场动画 ---------- */
.reveal { opacity: 0; transform: translateY(22px); transition: opacity .6s, transform .6s; }
.reveal.in { opacity: 1; transform: none; }

/* ---------- 404 ---------- */
.body-404 { display: flex; align-items: center; justify-content: center; min-height: 100vh; text-align: center; }
.box-404 h1 {
  font-size: 88px; font-weight: 800;
  background: var(--grad);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
}
.box-404 p { color: var(--ink-dim); margin: 14px 0 28px; }