/* =========================================================
   线和线 · 广西南宁聚高强网络科技有限公司
   全局样式 · 科技蓝主题 · H5 自适应
   ========================================================= */

/* ---------- 设计变量 ---------- */
:root {
  /* 主色：科技蓝渐变体系 */
  --c-navy-900: #06122b;
  --c-navy-800: #0a1c3d;
  --c-navy-700: #0d2552;
  --c-blue-600: #1e6bff;
  --c-blue-500: #2f7bff;
  --c-blue-400: #4f93ff;
  --c-cyan: #22d3ee;
  --c-cyan-soft: #7de7f5;

  /* 中性色 */
  --c-text: #1a2438;
  --c-text-soft: #5a6680;
  --c-text-mute: #8a94ad;
  --c-line: #e6ebf5;
  --c-bg: #ffffff;
  --c-bg-soft: #f5f8ff;
  --c-bg-mute: #eef3fc;

  /* 排版 */
  --font: "PingFang SC", "Microsoft YaHei", "Segoe UI", -apple-system, BlinkMacSystemFont, sans-serif;

  /* 尺寸 */
  --maxw: 1200px;
  --radius: 16px;
  --radius-sm: 10px;
  --header-h: 72px;

  /* 阴影 */
  --shadow-sm: 0 4px 16px rgba(13, 37, 82, 0.06);
  --shadow-md: 0 12px 32px rgba(13, 37, 82, 0.10);
  --shadow-lg: 0 24px 60px rgba(13, 37, 82, 0.16);

  /* 渐变 */
  --grad-blue: linear-gradient(135deg, var(--c-blue-600), var(--c-cyan));
  --grad-dark: linear-gradient(135deg, var(--c-navy-900), var(--c-navy-700) 60%, #123a7a);
}

/* ---------- 基础重置 ---------- */
* { margin: 0; padding: 0; box-sizing: border-box; }

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

body {
  font-family: var(--font);
  color: var(--c-text);
  background: var(--c-bg);
  line-height: 1.7;
  font-size: 16px;
  overflow-x: hidden;
}

img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }

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

.section { padding: 88px 0; }
.section--soft { background: var(--c-bg-soft); }
.section--dark { background: var(--grad-dark); color: #fff; }

.section-head { text-align: center; max-width: 720px; margin: 0 auto 56px; }
.section-head .eyebrow {
  display: inline-block;
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 2px;
  color: var(--c-blue-600);
  text-transform: uppercase;
  margin-bottom: 14px;
}
.section--dark .section-head .eyebrow { color: var(--c-cyan); }
.section-head h2 {
  font-size: clamp(26px, 4vw, 38px);
  font-weight: 800;
  letter-spacing: 0.5px;
  line-height: 1.3;
}
.section-head p { margin-top: 16px; color: var(--c-text-soft); font-size: 17px; }
.section--dark .section-head p { color: rgba(255, 255, 255, 0.72); }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 13px 28px;
  border-radius: 999px;
  font-size: 15px;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: transform .25s ease, box-shadow .25s ease, background .25s ease;
  white-space: nowrap;
}
.btn--primary { background: var(--grad-blue); color: #fff; box-shadow: 0 10px 24px rgba(30, 107, 255, 0.35); }
.btn--primary:hover { transform: translateY(-3px); box-shadow: 0 16px 32px rgba(30, 107, 255, 0.45); }
.btn--ghost { background: rgba(255, 255, 255, 0.12); color: #fff; border: 1px solid rgba(255, 255, 255, 0.4); }
.btn--ghost:hover { background: rgba(255, 255, 255, 0.22); transform: translateY(-3px); }
.btn--light { background: #fff; color: var(--c-blue-600); box-shadow: var(--shadow-md); }
.btn--light:hover { transform: translateY(-3px); box-shadow: var(--shadow-lg); }
.btn--outline { background: transparent; color: var(--c-blue-600); border: 1.5px solid var(--c-blue-600); }
.btn--outline:hover { background: var(--c-blue-600); color: #fff; transform: translateY(-3px); }

/* =========================================================
   顶部导航
   ========================================================= */
.header {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--header-h);
  z-index: 1000;
  display: flex;
  align-items: center;
  transition: background .3s ease, box-shadow .3s ease, backdrop-filter .3s ease;
}
.header.is-scrolled {
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  box-shadow: var(--shadow-sm);
}
.header__inner {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* 品牌 Logo */
.brand { display: flex; align-items: center; gap: 12px; }
.brand__mark { width: 40px; height: 40px; flex: none; }
.brand__text { display: flex; flex-direction: column; line-height: 1.15; }
.brand__name { font-size: 20px; font-weight: 800; letter-spacing: 1px; color: #fff; transition: color .3s ease; }
.brand__sub { font-size: 11px; color: rgba(255, 255, 255, 0.7); letter-spacing: .5px; transition: color .3s ease; }
.header.is-scrolled .brand__name { color: var(--c-navy-800); }
.header.is-scrolled .brand__sub { color: var(--c-text-mute); }

/* 导航菜单 */
.nav { display: flex; align-items: center; gap: 4px; }
.nav__link {
  position: relative;
  padding: 8px 16px;
  font-size: 15px;
  font-weight: 500;
  color: rgba(255, 255, 255, 0.88);
  border-radius: 8px;
  transition: color .25s ease;
}
.nav__link::after {
  content: "";
  position: absolute;
  left: 16px; right: 16px; bottom: 2px;
  height: 2px;
  background: var(--c-cyan);
  transform: scaleX(0);
  transform-origin: center;
  transition: transform .25s ease;
}
.nav__link:hover::after, .nav__link.is-active::after { transform: scaleX(1); }
.header.is-scrolled .nav__link { color: var(--c-text); }
.header.is-scrolled .nav__link.is-active { color: var(--c-blue-600); }
.nav__cta { margin-left: 12px; }

/* 汉堡按钮 */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 44px; height: 44px;
  background: transparent;
  border: none;
  cursor: pointer;
}
.nav-toggle span {
  display: block;
  width: 24px; height: 2px;
  background: #fff;
  border-radius: 2px;
  transition: transform .3s ease, opacity .3s ease, background .3s ease;
}
.header.is-scrolled .nav-toggle span { background: var(--c-navy-800); }
.nav-toggle.is-open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.is-open span:nth-child(2) { opacity: 0; }
.nav-toggle.is-open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* =========================================================
   页脚
   ========================================================= */
.footer { background: var(--c-navy-900); color: rgba(255, 255, 255, 0.7); padding: 64px 0 28px; }
.footer__grid {
  display: grid;
  grid-template-columns: 1.6fr 1fr 1fr 1.2fr;
  gap: 40px;
  padding-bottom: 40px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}
.footer__brand .brand__name { color: #fff; }
.footer__brand .brand__sub { color: rgba(255, 255, 255, 0.55); }
.footer__desc { margin-top: 18px; font-size: 14px; line-height: 1.8; max-width: 320px; }
.footer__col h4 { color: #fff; font-size: 16px; margin-bottom: 18px; font-weight: 600; }
.footer__col li { margin-bottom: 10px; font-size: 14px; }
.footer__col a:hover { color: var(--c-cyan); }
.footer__contact li { display: flex; gap: 8px; align-items: flex-start; }
.footer__bottom {
  padding-top: 24px;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 12px;
  font-size: 13px;
  color: rgba(255, 255, 255, 0.5);
}
.footer__bottom a:hover { color: var(--c-cyan); }
.footer__beian { display: inline-flex; align-items: center; gap: 6px; }

/* =========================================================
   通用页面横幅（非首页）
   ========================================================= */
.page-hero {
  position: relative;
  padding: calc(var(--header-h) + 80px) 0 80px;
  background: var(--grad-dark);
  color: #fff;
  text-align: center;
  overflow: hidden;
}
.page-hero::before,
.page-hero::after {
  content: "";
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: .5;
}
.page-hero::before { width: 380px; height: 380px; background: var(--c-blue-600); top: -120px; left: -80px; }
.page-hero::after { width: 320px; height: 320px; background: var(--c-cyan); bottom: -140px; right: -60px; opacity: .35; }
.page-hero__inner { position: relative; z-index: 1; }
.page-hero h1 { font-size: clamp(30px, 5vw, 46px); font-weight: 800; letter-spacing: 1px; }
.page-hero p { margin-top: 16px; font-size: 18px; color: rgba(255, 255, 255, 0.78); max-width: 640px; margin-left: auto; margin-right: auto; }
.breadcrumb { margin-top: 22px; font-size: 14px; color: rgba(255, 255, 255, 0.6); }
.breadcrumb a:hover { color: var(--c-cyan); }
.breadcrumb span { margin: 0 8px; }

/* =========================================================
   卡片网格通用
   ========================================================= */
.grid { display: grid; gap: 28px; }
.grid--3 { grid-template-columns: repeat(3, 1fr); }
.grid--4 { grid-template-columns: repeat(4, 1fr); }
.grid--2 { grid-template-columns: repeat(2, 1fr); }

.card {
  background: #fff;
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  padding: 34px 30px;
  transition: transform .3s ease, box-shadow .3s ease, border-color .3s ease;
}
.card:hover { transform: translateY(-8px); box-shadow: var(--shadow-md); border-color: transparent; }
.card__icon {
  width: 60px; height: 60px;
  border-radius: 14px;
  display: grid;
  place-items: center;
  background: var(--c-bg-mute);
  color: var(--c-blue-600);
  margin-bottom: 22px;
}
.card__icon svg { width: 30px; height: 30px; }
.card h3 { font-size: 20px; font-weight: 700; margin-bottom: 12px; }
.card p { color: var(--c-text-soft); font-size: 15px; }
.card__list { margin-top: 16px; }
.card__list li { position: relative; padding-left: 22px; font-size: 14px; color: var(--c-text-soft); margin-bottom: 8px; }
.card__list li::before {
  content: ""; position: absolute; left: 0; top: 9px;
  width: 8px; height: 8px; border-radius: 50%;
  background: var(--grad-blue);
}

/* =========================================================
   首页 Hero
   ========================================================= */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  background: var(--grad-dark);
  color: #fff;
  overflow: hidden;
  padding-top: var(--header-h);
}
/* 背景网格线 + 光斑 */
.hero__bg {
  position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.04) 1px, transparent 1px);
  background-size: 60px 60px;
  mask-image: radial-gradient(circle at 70% 40%, #000 0%, transparent 75%);
}
.hero__glow {
  position: absolute; border-radius: 50%; filter: blur(100px);
}
.hero__glow--1 { width: 500px; height: 500px; background: var(--c-blue-600); top: -100px; right: -60px; opacity: .45; }
.hero__glow--2 { width: 420px; height: 420px; background: var(--c-cyan); bottom: -120px; left: -80px; opacity: .25; }

.hero__inner {
  position: relative; z-index: 2;
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  align-items: center;
  gap: 48px;
}
.hero__badge {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 7px 16px;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: 999px;
  font-size: 13px;
  color: var(--c-cyan-soft);
  margin-bottom: 26px;
}
.hero__badge .dot { width: 7px; height: 7px; border-radius: 50%; background: var(--c-cyan); box-shadow: 0 0 8px var(--c-cyan); }
.hero h1 {
  font-size: clamp(34px, 5.4vw, 58px);
  font-weight: 800;
  line-height: 1.18;
  letter-spacing: 1px;
}
.hero h1 .grad { background: var(--grad-blue); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero__lead { margin-top: 22px; font-size: 18px; color: rgba(255, 255, 255, 0.78); max-width: 520px; }
.hero__actions { margin-top: 36px; display: flex; gap: 16px; flex-wrap: wrap; }

/* Hero 右侧可视化卡 */
.hero__visual { position: relative; }
.hero__panel {
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid rgba(255, 255, 255, 0.14);
  border-radius: 20px;
  padding: 28px;
  backdrop-filter: blur(8px);
  box-shadow: var(--shadow-lg);
}
.hero__panel-top { display: flex; gap: 7px; margin-bottom: 22px; }
.hero__panel-top i { width: 11px; height: 11px; border-radius: 50%; background: rgba(255,255,255,0.25); }
.hero__panel-top i:first-child { background: #ff5f57; }
.hero__panel-top i:nth-child(2) { background: #febc2e; }
.hero__panel-top i:nth-child(3) { background: #28c840; }
.hero__metric { display: flex; justify-content: space-between; align-items: flex-end; padding: 16px 0; border-bottom: 1px dashed rgba(255,255,255,0.12); }
.hero__metric:last-child { border-bottom: none; }
.hero__metric .k { font-size: 14px; color: rgba(255,255,255,0.6); }
.hero__metric .v { font-size: 26px; font-weight: 800; color: #fff; }
.hero__metric .v small { font-size: 14px; color: var(--c-cyan); margin-left: 4px; }
.hero__bars { display: flex; align-items: flex-end; gap: 10px; height: 90px; margin-top: 18px; }
.hero__bars span { flex: 1; background: var(--grad-blue); border-radius: 6px 6px 0 0; opacity: .85; }

/* 浮动小标签 */
.hero__chip {
  position: absolute;
  background: #fff; color: var(--c-navy-800);
  border-radius: 12px;
  padding: 12px 16px;
  font-size: 13px;
  font-weight: 600;
  box-shadow: var(--shadow-lg);
  display: flex; align-items: center; gap: 10px;
}
.hero__chip svg { width: 22px; height: 22px; color: var(--c-blue-600); }
.hero__chip--1 { top: -22px; left: -26px; animation: float 4s ease-in-out infinite; }
.hero__chip--2 { bottom: -20px; right: -18px; animation: float 4s ease-in-out infinite 1.5s; }
@keyframes float { 0%,100% { transform: translateY(0); } 50% { transform: translateY(-12px); } }

/* =========================================================
   数据统计条
   ========================================================= */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.stat { text-align: center; }
.stat__num { font-size: clamp(34px, 4vw, 48px); font-weight: 800; background: var(--grad-blue); -webkit-background-clip: text; background-clip: text; color: transparent; }
.stat__label { margin-top: 6px; color: var(--c-text-soft); font-size: 15px; }
.section--dark .stat__label { color: rgba(255,255,255,0.7); }

/* =========================================================
   解决方案 / 图文交错
   ========================================================= */
.feature { display: grid; grid-template-columns: 1fr 1fr; align-items: center; gap: 56px; }
.feature + .feature { margin-top: 80px; }
.feature--reverse .feature__media { order: 2; }
.feature__media {
  border-radius: var(--radius);
  background: var(--grad-blue);
  min-height: 320px;
  position: relative;
  overflow: hidden;
  display: grid; place-items: center;
  box-shadow: var(--shadow-md);
}
.feature__media svg { width: 50%; height: auto; color: rgba(255,255,255,0.92); }
.feature__media::after {
  content: ""; position: absolute; inset: 0;
  background-image: linear-gradient(rgba(255,255,255,0.08) 1px, transparent 1px), linear-gradient(90deg, rgba(255,255,255,0.08) 1px, transparent 1px);
  background-size: 36px 36px;
}
.feature__body .eyebrow { color: var(--c-blue-600); font-weight: 600; letter-spacing: 2px; font-size: 13px; text-transform: uppercase; }
.feature__body h3 { font-size: clamp(24px, 3vw, 32px); font-weight: 800; margin: 14px 0 16px; }
.feature__body p { color: var(--c-text-soft); }
.feature__body .card__list { margin-top: 22px; }
.feature__body .btn { margin-top: 28px; }

/* =========================================================
   流程步骤
   ========================================================= */
.steps { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; counter-reset: step; }
.step { position: relative; padding: 32px 24px; background: #fff; border-radius: var(--radius); border: 1px solid var(--c-line); }
.step__no {
  width: 48px; height: 48px; border-radius: 12px;
  background: var(--grad-blue); color: #fff;
  display: grid; place-items: center;
  font-weight: 800; font-size: 20px;
  margin-bottom: 18px;
}
.step h3 { font-size: 18px; margin-bottom: 10px; }
.step p { font-size: 14px; color: var(--c-text-soft); }

/* =========================================================
   案例卡片
   ========================================================= */
.case-card {
  border-radius: var(--radius);
  overflow: hidden;
  background: #fff;
  border: 1px solid var(--c-line);
  transition: transform .3s ease, box-shadow .3s ease;
}
.case-card:hover { transform: translateY(-8px); box-shadow: var(--shadow-md); }
.case-card__cover { height: 200px; display: grid; place-items: center; position: relative; }
.case-card__cover svg { width: 84px; height: 84px; color: rgba(255,255,255,0.9); }
.case-card__body { padding: 26px; }
.case-card__tag { display: inline-block; font-size: 12px; font-weight: 600; color: var(--c-blue-600); background: var(--c-bg-mute); padding: 4px 12px; border-radius: 999px; margin-bottom: 14px; }
.case-card__body h3 { font-size: 19px; margin-bottom: 10px; }
.case-card__body p { font-size: 14px; color: var(--c-text-soft); }
.case-card__meta { margin-top: 18px; display: flex; gap: 24px; }
.case-card__meta .v { font-size: 20px; font-weight: 800; color: var(--c-blue-600); }
.case-card__meta .k { font-size: 12px; color: var(--c-text-mute); }

/* 封面配色变体 */
.cover-a { background: linear-gradient(135deg, #1e6bff, #22d3ee); }
.cover-b { background: linear-gradient(135deg, #6a4cff, #1e6bff); }
.cover-c { background: linear-gradient(135deg, #0d9aa0, #22d3ee); }
.cover-d { background: linear-gradient(135deg, #ff6b6b, #ffb347); }
.cover-e { background: linear-gradient(135deg, #2b5876, #4e4376); }
.cover-f { background: linear-gradient(135deg, #11998e, #38ef7d); }

/* =========================================================
   新闻列表
   ========================================================= */
.news-card { display: flex; flex-direction: column; height: 100%; }
.news-card .case-card__cover { height: 180px; }
.news-card__date { font-size: 13px; color: var(--c-text-mute); margin-bottom: 10px; }
.news-card__body { padding: 24px; display: flex; flex-direction: column; flex: 1; }
.news-card__body h3 { font-size: 18px; margin-bottom: 10px; line-height: 1.4; }
.news-card__body p { font-size: 14px; color: var(--c-text-soft); flex: 1; }
.news-card__more { margin-top: 16px; color: var(--c-blue-600); font-weight: 600; font-size: 14px; }

/* =========================================================
   关于我们：价值观、团队、时间线
   ========================================================= */
.timeline { position: relative; max-width: 820px; margin: 0 auto; padding-left: 30px; }
.timeline::before { content: ""; position: absolute; left: 7px; top: 6px; bottom: 6px; width: 2px; background: var(--c-line); }
.timeline__item { position: relative; padding-bottom: 38px; }
.timeline__item:last-child { padding-bottom: 0; }
.timeline__item::before {
  content: ""; position: absolute; left: -30px; top: 4px;
  width: 16px; height: 16px; border-radius: 50%;
  background: var(--grad-blue);
  box-shadow: 0 0 0 4px rgba(30,107,255,0.15);
}
.timeline__year { font-size: 18px; font-weight: 800; color: var(--c-blue-600); }
.timeline__item h3 { font-size: 18px; margin: 6px 0 8px; }
.timeline__item p { color: var(--c-text-soft); font-size: 15px; }

/* =========================================================
   联系页
   ========================================================= */
.contact-grid { display: grid; grid-template-columns: 1fr 1.1fr; gap: 48px; align-items: start; }
.contact-info .info-item { display: flex; gap: 16px; padding: 22px 0; border-bottom: 1px solid var(--c-line); }
.contact-info .info-item:last-child { border-bottom: none; }
.contact-info .info-item__icon {
  width: 50px; height: 50px; flex: none; border-radius: 12px;
  display: grid; place-items: center;
  background: var(--c-bg-mute); color: var(--c-blue-600);
}
.contact-info .info-item__icon svg { width: 24px; height: 24px; }
.contact-info .info-item h4 { font-size: 16px; margin-bottom: 4px; }
.contact-info .info-item p { color: var(--c-text-soft); font-size: 15px; }

.form-card { background: #fff; border: 1px solid var(--c-line); border-radius: var(--radius); padding: 38px; box-shadow: var(--shadow-sm); }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.form-group { margin-bottom: 18px; }
.form-group label { display: block; font-size: 14px; font-weight: 600; margin-bottom: 8px; }
.form-group input, .form-group textarea, .form-group select {
  width: 100%;
  padding: 13px 16px;
  border: 1px solid var(--c-line);
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-family: inherit;
  background: var(--c-bg-soft);
  transition: border-color .2s ease, box-shadow .2s ease, background .2s ease;
}
.form-group input:focus, .form-group textarea:focus, .form-group select:focus {
  outline: none;
  border-color: var(--c-blue-600);
  background: #fff;
  box-shadow: 0 0 0 3px rgba(30,107,255,0.12);
}
.form-group textarea { resize: vertical; min-height: 120px; }
.form-note { font-size: 13px; color: var(--c-text-mute); margin-top: 14px; }
.form-tip { display: none; margin-top: 16px; padding: 12px 16px; border-radius: var(--radius-sm); background: #e8f7ee; color: #1a7f4b; font-size: 14px; }
.form-tip.is-show { display: block; }

/* 地图占位 */
.map-box { margin-top: 0; border-radius: var(--radius); overflow: hidden; border: 1px solid var(--c-line); height: 280px; background: var(--c-bg-mute); display: grid; place-items: center; color: var(--c-text-mute); position: relative; }
.map-box svg { width: 64px; height: 64px; color: var(--c-blue-400); }

/* =========================================================
   CTA 区
   ========================================================= */
.cta {
  background: var(--grad-blue);
  border-radius: 24px;
  padding: 56px;
  text-align: center;
  color: #fff;
  position: relative;
  overflow: hidden;
}
.cta::before { content: ""; position: absolute; inset: 0; background-image: linear-gradient(rgba(255,255,255,0.08) 1px, transparent 1px), linear-gradient(90deg, rgba(255,255,255,0.08) 1px, transparent 1px); background-size: 40px 40px; }
.cta__inner { position: relative; z-index: 1; }
.cta h2 { font-size: clamp(26px, 4vw, 36px); font-weight: 800; }
.cta p { margin-top: 14px; font-size: 17px; color: rgba(255,255,255,0.9); }
.cta .btn { margin-top: 28px; }

/* =========================================================
   回到顶部
   ========================================================= */
.to-top {
  position: fixed; right: 24px; bottom: 24px;
  width: 48px; height: 48px;
  border-radius: 50%;
  background: var(--grad-blue);
  color: #fff;
  border: none;
  display: grid; place-items: center;
  cursor: pointer;
  box-shadow: var(--shadow-md);
  opacity: 0; visibility: hidden; transform: translateY(12px);
  transition: opacity .3s ease, transform .3s ease, visibility .3s ease;
  z-index: 900;
}
.to-top.is-show { opacity: 1; visibility: visible; transform: translateY(0); }
.to-top svg { width: 22px; height: 22px; }

/* =========================================================
   滚动入场动画
   ========================================================= */
.reveal { opacity: 0; transform: translateY(30px); transition: opacity .7s ease, transform .7s ease; }
.reveal.is-in { opacity: 1; transform: translateY(0); }
.reveal[data-delay="1"] { transition-delay: .1s; }
.reveal[data-delay="2"] { transition-delay: .2s; }
.reveal[data-delay="3"] { transition-delay: .3s; }

/* =========================================================
   响应式
   ========================================================= */
@media (max-width: 992px) {
  .hero__inner { grid-template-columns: 1fr; gap: 40px; }
  .hero__visual { max-width: 460px; }
  .grid--4 { grid-template-columns: repeat(2, 1fr); }
  .steps { grid-template-columns: repeat(2, 1fr); }
  .footer__grid { grid-template-columns: 1fr 1fr; }
  .feature, .feature--reverse { grid-template-columns: 1fr; gap: 32px; }
  .feature--reverse .feature__media { order: 0; }
  .contact-grid { grid-template-columns: 1fr; gap: 32px; }
}

@media (max-width: 768px) {
  .section { padding: 60px 0; }
  .nav {
    position: fixed;
    top: var(--header-h); left: 0; right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: rgba(8, 18, 43, 0.98);
    backdrop-filter: blur(12px);
    padding: 12px 20px 24px;
    transform: translateY(-130%);
    transition: transform .35s ease;
    box-shadow: var(--shadow-lg);
    max-height: calc(100vh - var(--header-h));
    overflow-y: auto;
  }
  .nav.is-open { transform: translateY(0); }
  .nav__link { color: #fff; padding: 14px 8px; border-bottom: 1px solid rgba(255,255,255,0.08); border-radius: 0; }
  .nav__link::after { display: none; }
  .nav__link.is-active { color: var(--c-cyan); }
  .nav__cta { margin: 16px 0 0; }
  .nav__cta .btn { width: 100%; justify-content: center; }
  .nav-toggle { display: flex; }
  /* 移动端导航展开时强制深色按钮可见 */
  .header.is-scrolled.nav-open .nav-toggle span { background: #fff; }

  .grid--3, .grid--4, .grid--2 { grid-template-columns: 1fr; }
  .stats { grid-template-columns: repeat(2, 1fr); gap: 28px 16px; }
  .steps { grid-template-columns: 1fr; }
  .form-row { grid-template-columns: 1fr; }
  .footer__grid { grid-template-columns: 1fr; gap: 28px; }
  .cta { padding: 40px 24px; }
  .hero__chip { display: none; }
  .container { padding: 0 18px; }
  .footer__bottom { flex-direction: column; align-items: flex-start; }
}

@media (max-width: 420px) {
  .stats { grid-template-columns: 1fr; }
  .brand__sub { display: none; }
}