/* ===== 赵露思AI换脸视频社区 · 共享样式系统 ===== */

/* ---------- 设计变量 ---------- */
:root {
  --c-bg: #0b0414;
  --c-bg-soft: #14092a;
  --c-surface: rgba(255, 255, 255, 0.06);
  --c-surface-strong: rgba(255, 255, 255, 0.1);
  --c-border: rgba(255, 255, 255, 0.12);
  --c-text: #f4f1ff;
  --c-text-soft: #c5bcd9;
  --c-text-mute: #8b80a3;

  --c-primary: #8b5cf6;
  --c-primary-2: #ec4899;
  --c-accent: #22d3ee;
  --c-warn: #f59e0b;

  --grad-hero: linear-gradient(135deg, #7c3aed 0%, #ec4899 50%, #f59e0b 100%);
  --grad-primary: linear-gradient(120deg, #8b5cf6 0%, #ec4899 100%);
  --grad-accent: linear-gradient(120deg, #22d3ee 0%, #8b5cf6 100%);

  --shadow-soft: 0 10px 40px rgba(0, 0, 0, 0.35);
  --shadow-glow: 0 0 40px rgba(139, 92, 246, 0.45);
  --shadow-card: 0 8px 32px rgba(0, 0, 0, 0.25);

  --radius-sm: 10px;
  --radius: 16px;
  --radius-lg: 24px;

  --container: 1200px;
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

/* ---------- 重置与基础 ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

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

body {
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: var(--c-bg);
  color: var(--c-text);
  line-height: 1.7;
  overflow-x: hidden;
  min-height: 100vh;
  position: relative;
}

/* 背景光晕装饰 */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  background:
    radial-gradient(60vw 60vw at 10% -10%, rgba(124, 58, 237, 0.35), transparent 60%),
    radial-gradient(50vw 50vw at 100% 0%, rgba(236, 72, 153, 0.28), transparent 55%),
    radial-gradient(60vw 60vw at 50% 120%, rgba(34, 211, 238, 0.18), transparent 60%);
  pointer-events: none;
  z-index: -1;
}

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

/* ---------- 布局容器 ---------- */
.container { width: 100%; max-width: var(--container); margin: 0 auto; padding: 0 24px; }

.section { padding: 88px 0; position: relative; }
.section--tight { padding: 56px 0; }

/* ---------- 排版 ---------- */
h1, h2, h3, h4 { line-height: 1.25; font-weight: 800; letter-spacing: -0.02em; }
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  font-size: 13px; font-weight: 600; letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--c-accent);
  padding: 6px 14px; border-radius: 999px;
  background: rgba(34, 211, 238, 0.1); border: 1px solid rgba(34, 211, 238, 0.25);
  margin-bottom: 18px;
}
.section-title { font-size: clamp(28px, 4vw, 44px); }
.section-sub { color: var(--c-text-soft); font-size: clamp(15px, 2vw, 18px); max-width: 640px; margin-top: 14px; }
.section-head { margin-bottom: 48px; }
.section-head--center { text-align: center; }
.section-head--center .section-sub { margin-left: auto; margin-right: auto; }

/* ---------- 导航 ---------- */
.nav {
  position: sticky; top: 0; z-index: 100;
  background: rgba(11, 4, 20, 0.72);
  backdrop-filter: blur(18px); -webkit-backdrop-filter: blur(18px);
  border-bottom: 1px solid var(--c-border);
}
.nav__inner { display: flex; align-items: center; justify-content: space-between; height: 68px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 800; font-size: 19px; }
.brand__logo {
  width: 36px; height: 36px; border-radius: 10px;
  background: var(--grad-primary);
  display: grid; place-items: center; font-size: 18px;
  box-shadow: var(--shadow-glow);
}
.brand__name b { background: var(--grad-primary); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }

.nav__links { display: flex; align-items: center; gap: 6px; }
.nav__link {
  font-size: 15px; font-weight: 500; color: var(--c-text-soft);
  padding: 8px 16px; border-radius: 999px; transition: all .25s var(--ease);
}
.nav__link:hover { color: var(--c-text); background: var(--c-surface); }
.nav__link.active { color: #fff; background: var(--c-surface-strong); }

.nav__cta { display: flex; align-items: center; gap: 12px; }

.nav__toggle { display: none; width: 42px; height: 42px; border-radius: 10px; align-items: center; justify-content: center; }
.nav__toggle span { position: relative; width: 22px; height: 2px; background: var(--c-text); border-radius: 2px; transition: .3s; }
.nav__toggle span::before, .nav__toggle span::after {
  content: ""; position: absolute; left: 0; width: 22px; height: 2px; background: var(--c-text); border-radius: 2px; transition: .3s;
}
.nav__toggle span::before { top: -7px; }
.nav__toggle span::after { top: 7px; }
.nav__toggle.open span { background: transparent; }
.nav__toggle.open span::before { top: 0; transform: rotate(45deg); }
.nav__toggle.open span::after { top: 0; transform: rotate(-45deg); }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  font-size: 15px; font-weight: 600;
  padding: 13px 26px; border-radius: 999px;
  transition: all .25s var(--ease); white-space: nowrap; cursor: pointer;
  border: 1px solid transparent;
}
.btn--primary { background: var(--grad-primary); color: #fff; box-shadow: 0 8px 24px rgba(236, 72, 153, 0.35); }
.btn--primary:hover { transform: translateY(-2px); box-shadow: 0 12px 32px rgba(236, 72, 153, 0.5); }
.btn--ghost { background: var(--c-surface); color: var(--c-text); border-color: var(--c-border); }
.btn--ghost:hover { background: var(--c-surface-strong); transform: translateY(-2px); }
.btn--accent { background: var(--grad-accent); color: #06121a; }
.btn--accent:hover { transform: translateY(-2px); box-shadow: 0 12px 32px rgba(34, 211, 238, 0.4); }
.btn--lg { padding: 16px 32px; font-size: 16px; }
.btn--block { width: 100%; }

/* ---------- Hero ---------- */
.hero { position: relative; padding: 96px 0 72px; overflow: hidden; }
.hero__grid { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 56px; align-items: center; }
.hero__tag {
  display: inline-flex; align-items: center; gap: 8px; font-size: 13px; font-weight: 600;
  color: #ffd9ec; background: rgba(236, 72, 153, 0.12); border: 1px solid rgba(236, 72, 153, 0.3);
  padding: 7px 14px; border-radius: 999px; margin-bottom: 24px;
}
.hero__dot { width: 8px; height: 8px; border-radius: 50%; background: #ec4899; box-shadow: 0 0 10px #ec4899; animation: pulse 2s infinite; }
.hero h1 { font-size: clamp(34px, 5.5vw, 60px); line-height: 1.1; margin-bottom: 22px; }
.hero h1 .hl { background: var(--grad-primary); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }
.hero__desc { font-size: clamp(16px, 2vw, 19px); color: var(--c-text-soft); max-width: 560px; margin-bottom: 32px; }
.hero__actions { display: flex; flex-wrap: wrap; gap: 14px; }
.hero__stats { display: flex; gap: 36px; margin-top: 44px; flex-wrap: wrap; }
.hero__stat b { display: block; font-size: 30px; font-weight: 800; background: var(--grad-primary); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }
.hero__stat span { font-size: 13px; color: var(--c-text-mute); }

/* Hero 视觉卡 */
.hero__visual { position: relative; }
.hero__card {
  position: relative; border-radius: var(--radius-lg); overflow: hidden;
  background: var(--grad-hero); padding: 36px; min-height: 360px;
  box-shadow: var(--shadow-glow), var(--shadow-soft);
  display: flex; flex-direction: column; justify-content: flex-end;
}
.hero__card::before {
  content: ""; position: absolute; inset: 0;
  background: radial-gradient(circle at 30% 20%, rgba(255,255,255,.3), transparent 50%);
}
.hero__card-label { position: relative; font-size: 14px; font-weight: 600; opacity: .9; }
.hero__card-title { position: relative; font-size: 26px; font-weight: 800; margin: 6px 0; }
.hero__card-meta { position: relative; font-size: 13px; opacity: .85; }
.hero__chip {
  position: absolute; top: 24px; right: 24px;
  background: rgba(0,0,0,.35); backdrop-filter: blur(8px);
  border: 1px solid rgba(255,255,255,.2); border-radius: 999px;
  padding: 6px 14px; font-size: 12px; font-weight: 600;
}
.hero__float {
  position: absolute; background: rgba(20, 9, 42, 0.85); backdrop-filter: blur(12px);
  border: 1px solid var(--c-border); border-radius: 14px; padding: 12px 16px;
  box-shadow: var(--shadow-soft); display: flex; align-items: center; gap: 10px; font-size: 13px; font-weight: 600;
}
.hero__float-1 { top: 18px; left: -28px; animation: float 5s ease-in-out infinite; }
.hero__float-2 { bottom: 30px; right: -24px; animation: float 5s ease-in-out infinite .8s; }
.hero__float i { font-style: normal; font-size: 20px; }

@keyframes float { 0%,100% { transform: translateY(0); } 50% { transform: translateY(-12px); } }
@keyframes pulse { 0%,100% { opacity: 1; transform: scale(1); } 50% { opacity: .5; transform: scale(1.3); } }

/* ---------- 卡片通用 ---------- */
.card {
  background: var(--c-surface); border: 1px solid var(--c-border);
  border-radius: var(--radius); padding: 28px;
  transition: all .3s var(--ease); backdrop-filter: blur(10px);
}
.card:hover { transform: translateY(-4px); border-color: rgba(139, 92, 246, 0.5); box-shadow: var(--shadow-card); }
.card__icon {
  width: 52px; height: 52px; border-radius: 14px; display: grid; place-items: center;
  font-size: 24px; margin-bottom: 18px;
  background: var(--grad-primary); color: #fff;
}
.card h3 { font-size: 19px; margin-bottom: 10px; }
.card p { color: var(--c-text-soft); font-size: 15px; }

/* ---------- 特性网格 ---------- */
.grid { display: grid; gap: 24px; }
.grid--3 { grid-template-columns: repeat(3, 1fr); }
.grid--4 { grid-template-columns: repeat(4, 1fr); }
.grid--2 { grid-template-columns: repeat(2, 1fr); }

/* ---------- 视频卡片 ---------- */
.video-card { display: flex; flex-direction: column; border-radius: var(--radius); overflow: hidden; background: var(--c-surface); border: 1px solid var(--c-border); transition: all .3s var(--ease); }
.video-card:hover { transform: translateY(-4px); border-color: rgba(236, 72, 153, 0.45); box-shadow: var(--shadow-card); }
.video-card__thumb { position: relative; aspect-ratio: 16/9; background: var(--grad-hero); display: grid; place-items: center; overflow: hidden; }
.video-card__thumb .play { width: 56px; height: 56px; border-radius: 50%; background: rgba(0,0,0,.45); backdrop-filter: blur(8px); display: grid; place-items: center; font-size: 22px; transition: .25s; }
.video-card:hover .play { transform: scale(1.1); background: var(--grad-primary); }
.video-card__tag { position: absolute; top: 12px; left: 12px; background: rgba(0,0,0,.55); backdrop-filter: blur(6px); border-radius: 8px; padding: 4px 10px; font-size: 12px; font-weight: 600; }
.video-card__dur { position: absolute; bottom: 12px; right: 12px; background: rgba(0,0,0,.55); border-radius: 6px; padding: 3px 8px; font-size: 12px; }
.video-card__body { padding: 18px; flex: 1; display: flex; flex-direction: column; }
.video-card__title { font-size: 16px; font-weight: 700; margin-bottom: 8px; line-height: 1.4; }
.video-card__meta { display: flex; align-items: center; gap: 10px; color: var(--c-text-mute); font-size: 13px; margin-top: auto; padding-top: 12px; }
.video-card__avatar { width: 26px; height: 26px; border-radius: 50%; background: var(--grad-accent); display: grid; place-items: center; font-size: 12px; font-weight: 700; color: #06121a; }

/* ---------- 标签/徽章 ---------- */
.chip { display: inline-flex; align-items: center; gap: 6px; font-size: 12px; font-weight: 600; padding: 5px 12px; border-radius: 999px; background: var(--c-surface); border: 1px solid var(--c-border); color: var(--c-text-soft); }
.chip--hot { color: #ff6b9d; background: rgba(236, 72, 153, 0.12); border-color: rgba(236, 72, 153, 0.3); }
.chip--new { color: var(--c-accent); background: rgba(34, 211, 238, 0.12); border-color: rgba(34, 211, 238, 0.3); }
.chip--ai { color: #c4b5fd; background: rgba(139, 92, 246, 0.15); border-color: rgba(139, 92, 246, 0.35); }

/* ---------- CTA 横幅 ---------- */
.cta-banner {
  position: relative; border-radius: var(--radius-lg); overflow: hidden;
  background: var(--grad-hero); padding: 56px; text-align: center;
  box-shadow: var(--shadow-glow);
}
.cta-banner::before { content: ""; position: absolute; inset: 0; background: radial-gradient(circle at 50% 0%, rgba(255,255,255,.25), transparent 50%); }
.cta-banner h2 { position: relative; font-size: clamp(26px, 3.5vw, 38px); margin-bottom: 14px; }
.cta-banner p { position: relative; opacity: .95; max-width: 540px; margin: 0 auto 28px; }
.cta-banner .hero__actions { position: relative; justify-content: center; }

/* ---------- 页脚 ---------- */
.footer { border-top: 1px solid var(--c-border); padding: 56px 0 28px; margin-top: 40px; background: rgba(11,4,20,.5); }
.footer__grid { display: grid; grid-template-columns: 1.6fr 1fr 1fr 1fr; gap: 40px; margin-bottom: 40px; }
.footer__about p { color: var(--c-text-mute); font-size: 14px; margin: 14px 0 18px; max-width: 320px; }
.footer h4 { font-size: 14px; margin-bottom: 16px; color: var(--c-text); }
.footer ul li { margin-bottom: 10px; }
.footer ul a { color: var(--c-text-mute); font-size: 14px; transition: color .2s; }
.footer ul a:hover { color: var(--c-accent); }
.footer__social { display: flex; gap: 10px; }
.footer__social a { width: 38px; height: 38px; border-radius: 10px; background: var(--c-surface); border: 1px solid var(--c-border); display: grid; place-items: center; font-size: 16px; transition: .25s; }
.footer__social a:hover { background: var(--grad-primary); transform: translateY(-3px); }
.footer__bottom { border-top: 1px solid var(--c-border); padding-top: 24px; display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 12px; color: var(--c-text-mute); font-size: 13px; }
.footer__bottom a { color: var(--c-text-mute); }
.footer__bottom a:hover { color: var(--c-accent); }

/* ---------- 面包屑 ---------- */
.breadcrumb { display: flex; align-items: center; gap: 8px; font-size: 14px; color: var(--c-text-mute); padding: 24px 0; }
.breadcrumb a { color: var(--c-text-mute); }
.breadcrumb a:hover { color: var(--c-accent); }
.breadcrumb span { opacity: .5; }

/* ---------- 页面通用头部 ---------- */
.page-head { padding: 56px 0 32px; }
.page-head h1 { font-size: clamp(30px, 4.5vw, 48px); margin-bottom: 14px; }
.page-head p { color: var(--c-text-soft); font-size: clamp(15px, 2vw, 18px); max-width: 680px; }

/* ---------- 过滤栏 ---------- */
.filter-bar { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; justify-content: space-between; margin-bottom: 36px; padding: 18px 22px; background: var(--c-surface); border: 1px solid var(--c-border); border-radius: var(--radius); }
.filter-tabs { display: flex; gap: 8px; flex-wrap: wrap; }
.filter-tab { font-size: 14px; font-weight: 600; padding: 8px 16px; border-radius: 999px; background: transparent; border: 1px solid var(--c-border); color: var(--c-text-soft); transition: .25s; }
.filter-tab:hover { color: var(--c-text); }
.filter-tab.active { background: var(--grad-primary); color: #fff; border-color: transparent; }
.filter-search { display: flex; align-items: center; gap: 8px; background: var(--c-bg-soft); border: 1px solid var(--c-border); border-radius: 999px; padding: 8px 16px; }
.filter-search input { background: transparent; border: none; outline: none; color: var(--c-text); font-size: 14px; width: 180px; }
.filter-search input::placeholder { color: var(--c-text-mute); }

/* ---------- 视频播放器 ---------- */
.player-wrap { position: relative; border-radius: var(--radius-lg); overflow: hidden; background: #000; aspect-ratio: 16/9; box-shadow: var(--shadow-soft); }
.player-wrap .player-poster { position: absolute; inset: 0; background: var(--grad-hero); display: grid; place-items: center; }
.player-wrap .player-poster .big-play { width: 84px; height: 84px; border-radius: 50%; background: rgba(0,0,0,.5); backdrop-filter: blur(10px); border: 2px solid rgba(255,255,255,.4); display: grid; place-items: center; font-size: 34px; transition: .3s; cursor: pointer; }
.player-wrap .player-poster .big-play:hover { transform: scale(1.1); background: var(--grad-primary); }
.player-controls { position: absolute; bottom: 0; left: 0; right: 0; padding: 20px; background: linear-gradient(transparent, rgba(0,0,0,.8)); }
.player-progress { height: 4px; background: rgba(255,255,255,.2); border-radius: 2px; cursor: pointer; margin-bottom: 12px; position: relative; }
.player-progress__fill { height: 100%; width: 32%; background: var(--grad-primary); border-radius: 2px; }
.player-progress__knob { position: absolute; top: 50%; left: 32%; transform: translate(-50%,-50%); width: 12px; height: 12px; border-radius: 50%; background: #fff; }
.player-bar { display: flex; align-items: center; justify-content: space-between; color: #fff; font-size: 13px; }

/* ---------- 视频信息卡 ---------- */
.watch-layout { display: grid; grid-template-columns: 1fr 340px; gap: 36px; align-items: start; }
.watch-info h1 { font-size: clamp(22px, 3vw, 30px); margin: 18px 0 12px; line-height: 1.35; }
.watch-info__meta { display: flex; align-items: center; gap: 16px; color: var(--c-text-mute); font-size: 14px; margin-bottom: 22px; flex-wrap: wrap; }
.watch-info__meta .sep { width: 4px; height: 4px; border-radius: 50%; background: var(--c-text-mute); }
.watch-actions { display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 26px; }
.action-btn { display: inline-flex; align-items: center; gap: 8px; padding: 9px 16px; border-radius: 999px; background: var(--c-surface); border: 1px solid var(--c-border); font-size: 14px; font-weight: 600; color: var(--c-text-soft); transition: .25s; }
.action-btn:hover { background: var(--c-surface-strong); color: var(--c-text); transform: translateY(-2px); }
.action-btn i { font-style: normal; font-size: 16px; }

.watch-desc { background: var(--c-surface); border: 1px solid var(--c-border); border-radius: var(--radius); padding: 22px; font-size: 15px; color: var(--c-text-soft); line-height: 1.8; }
.watch-desc h4 { color: var(--c-text); margin-bottom: 12px; font-size: 15px; }

/* 侧栏推荐 */
.rec-card { display: flex; gap: 12px; padding: 14px; border-radius: 12px; transition: .25s; }
.rec-card:hover { background: var(--c-surface); }
.rec-card__thumb { width: 130px; flex-shrink: 0; aspect-ratio: 16/9; border-radius: 8px; background: var(--grad-hero); position: relative; }
.rec-card__thumb .dur { position: absolute; bottom: 6px; right: 6px; background: rgba(0,0,0,.6); border-radius: 4px; font-size: 10px; padding: 2px 6px; }
.rec-card__title { font-size: 14px; font-weight: 600; line-height: 1.4; margin-bottom: 6px; }
.rec-card__meta { font-size: 12px; color: var(--c-text-mute); }

/* ---------- 下载页 ---------- */
.dl-hero { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: center; }
.dl-visual { position: relative; display: grid; place-items: center; min-height: 420px; }
.phone-mock { width: 260px; aspect-ratio: 9/19; border-radius: 38px; background: #1a1030; border: 3px solid #2a1d44; box-shadow: var(--shadow-glow), var(--shadow-soft); padding: 14px; position: relative; }
.phone-mock::before { content: ""; position: absolute; top: 14px; left: 50%; transform: translateX(-50%); width: 90px; height: 22px; background: #0b0414; border-radius: 0 0 14px 14px; }
.phone-screen { width: 100%; height: 100%; border-radius: 26px; background: var(--grad-hero); overflow: hidden; display: flex; flex-direction: column; justify-content: flex-end; padding: 20px; }
.phone-screen .ph-label { font-size: 12px; opacity: .85; }
.phone-screen .ph-title { font-size: 18px; font-weight: 800; margin: 4px 0; }
.phone-float { position: absolute; background: rgba(20,9,42,.9); backdrop-filter: blur(12px); border: 1px solid var(--c-border); border-radius: 14px; padding: 12px 16px; box-shadow: var(--shadow-soft); font-size: 13px; font-weight: 600; display: flex; align-items: center; gap: 10px; }
.phone-float-1 { top: 30px; right: -10px; animation: float 5s ease-in-out infinite; }
.phone-float-2 { bottom: 50px; left: -16px; animation: float 5s ease-in-out infinite .6s; }

.dl-os { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.dl-os-card { background: var(--c-surface); border: 1px solid var(--c-border); border-radius: var(--radius); padding: 32px 24px; text-align: center; transition: .3s; }
.dl-os-card:hover { transform: translateY(-4px); border-color: rgba(139,92,246,.5); box-shadow: var(--shadow-card); }
.dl-os-card__icon { font-size: 40px; margin-bottom: 14px; }
.dl-os-card h3 { font-size: 18px; margin-bottom: 6px; }
.dl-os-card p { font-size: 13px; color: var(--c-text-mute); margin-bottom: 18px; }
.dl-os-card .btn { width: 100%; }

.feature-list { display: grid; grid-template-columns: repeat(3,1fr); gap: 20px; }
.feature-item { display: flex; gap: 14px; align-items: flex-start; }
.feature-item__icon { width: 44px; height: 44px; border-radius: 12px; background: rgba(34,211,238,.12); border: 1px solid rgba(34,211,238,.3); display: grid; place-items: center; font-size: 20px; flex-shrink: 0; }
.feature-item h4 { font-size: 15px; margin-bottom: 4px; }
.feature-item p { font-size: 13px; color: var(--c-text-mute); }

/* ---------- 技术/关于页 ---------- */
.tech-step { display: grid; grid-template-columns: 60px 1fr; gap: 24px; align-items: start; }
.tech-step__num { width: 52px; height: 52px; border-radius: 14px; background: var(--grad-primary); display: grid; place-items: center; font-size: 22px; font-weight: 800; color: #fff; box-shadow: var(--shadow-glow); }
.tech-step h3 { font-size: 20px; margin-bottom: 8px; }
.tech-step p { color: var(--c-text-soft); font-size: 15px; }

.stat-grid { display: grid; grid-template-columns: repeat(4,1fr); gap: 20px; }
.stat-box { text-align: center; padding: 32px 18px; background: var(--c-surface); border: 1px solid var(--c-border); border-radius: var(--radius); }
.stat-box b { display: block; font-size: 38px; font-weight: 800; background: var(--grad-primary); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent; }
.stat-box span { font-size: 13px; color: var(--c-text-mute); }

.qa-item { background: var(--c-surface); border: 1px solid var(--c-border); border-radius: var(--radius); margin-bottom: 14px; overflow: hidden; }
.qa-item summary { padding: 20px 24px; font-size: 16px; font-weight: 600; cursor: pointer; list-style: none; display: flex; justify-content: space-between; align-items: center; }
.qa-item summary::-webkit-details-marker { display: none; }
.qa-item summary::after { content: "+"; font-size: 22px; color: var(--c-accent); transition: .25s; }
.qa-item[open] summary::after { transform: rotate(45deg); }
.qa-item p { padding: 0 24px 22px; color: var(--c-text-soft); font-size: 15px; }

/* ---------- 揭示动画 ---------- */
.reveal { opacity: 0; transform: translateY(28px); transition: opacity .7s var(--ease), transform .7s var(--ease); }
.reveal.in { opacity: 1; transform: none; }

/* ---------- 响应式 ---------- */
@media (max-width: 980px) {
  .hero__grid { grid-template-columns: 1fr; gap: 40px; }
  .hero__visual { max-width: 460px; }
  .dl-hero { grid-template-columns: 1fr; }
  .dl-visual { order: -1; min-height: 380px; }
  .watch-layout { grid-template-columns: 1fr; }
  .footer__grid { grid-template-columns: 1fr 1fr; gap: 30px; }
  .grid--4 { grid-template-columns: repeat(2, 1fr); }
  .stat-grid { grid-template-columns: repeat(2,1fr); }
  .feature-list { grid-template-columns: 1fr; }
}

@media (max-width: 720px) {
  .nav__links, .nav__cta .btn--ghost { display: none; }
  .nav__toggle { display: flex; }
  .nav__links.mobile-open {
    display: flex; position: absolute; top: 68px; left: 0; right: 0;
    flex-direction: column; align-items: stretch; gap: 0;
    background: rgba(11,4,20,.98); backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--c-border); padding: 12px 24px;
  }
  .nav__links.mobile-open .nav__link { padding: 14px 16px; border-radius: 10px; }
  .nav__links.mobile-open .nav__cta { display: flex; }
  .section { padding: 60px 0; }
  .hero { padding: 56px 0; }
  .grid--3, .grid--2 { grid-template-columns: 1fr; }
  .grid--4 { grid-template-columns: 1fr; }
  .stat-grid { grid-template-columns: 1fr 1fr; }
  .dl-os { grid-template-columns: 1fr; }
  .cta-banner { padding: 36px 24px; }
  .hero__stats { gap: 24px; }
  .filter-bar { flex-direction: column; align-items: stretch; }
  .filter-search input { width: 100%; }
  .footer__grid { grid-template-columns: 1fr; }
  .footer__bottom { flex-direction: column; text-align: center; }
  .container { padding: 0 18px; }
}

@media (max-width: 420px) {
  .stat-grid { grid-template-columns: 1fr; }
}