/* ============================================================================
   theme.css —— 锋尚汽配公共设计令牌与组件（供前台 / 后台复用）
   令牌来源：design4-tech-blue.html（Tech Blue Gradient）
   仅包含「共享层」：设计令牌 / 基础重置 / 导航栏 / 按钮 / 玻璃卡 / 区块头 /
   页脚 / 语言分段控件 / 响应式断点。页面专有样式放 home.css / products.css / admin.css。
   ============================================================================ */

:root {
  /* 品牌色与渐变 */
  --fs-primary: #3b82f6;
  --fs-primary-light: #93c5fd;
  --fs-accent: #06b6d4;
  --fs-grad: linear-gradient(135deg, #3b82f6, #06b6d4);
  --fs-grad-text: linear-gradient(135deg, #1e293b, #3b82f6);

  /* 中性色 */
  --fs-bg: #f8fafc;
  --fs-surface: #ffffff;
  --fs-dark: #0f172a;
  --fs-dark-2: #1e3a5f;
  --fs-text: #1e293b;
  --fs-text-strong: #0f172a;
  --fs-muted: #64748b;
  --fs-muted-2: #94a3b8;
  --fs-line: rgba(0, 0, 0, 0.06);
  --fs-line-light: #f1f5f9;

  /* 圆角 */
  --fs-radius: 20px;
  --fs-radius-sm: 16px;
  --fs-radius-lg: 24px;
  --fs-radius-pill: 25px;

  /* 阴影 */
  --fs-shadow-sm: 0 4px 14px rgba(59, 130, 246, 0.3);
  --fs-shadow: 0 20px 60px rgba(59, 130, 246, 0.1);
  --fs-shadow-lg: 0 12px 30px rgba(59, 130, 246, 0.4);

  /* 字体栈 */
  --fs-font-en: 'Segoe UI', 'Microsoft YaHei', sans-serif;
  --fs-font-zh: 'Microsoft YaHei', 'PingFang SC', sans-serif;

  /* 间距 */
  --fs-gap: 40px;
  --fs-maxw: 1400px;
}

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

body {
  font-family: var(--fs-font-en);
  color: var(--fs-text);
  background: var(--fs-bg);
  overflow-x: hidden;
  line-height: 1.6;
}

/* 中文语言下切换字体栈（i18n.setLang 会挂 .lang-zh 到 body） */
body.lang-zh { font-family: var(--fs-font-zh); }

h1, h2, h3, h4 { letter-spacing: -0.5px; }
a { color: inherit; }
img { max-width: 100%; display: block; }
button { font-family: inherit; }

/* ===== 导航栏 ===== */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--fs-line);
}
.nav-inner {
  max-width: var(--fs-maxw);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 40px;
}
.logo { display: flex; align-items: center; gap: 12px; text-decoration: none; }
.logo-orb {
  width: 40px; height: 40px;
  background: var(--fs-grad);
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  color: #fff; font-weight: 900; font-size: 18px;
  box-shadow: var(--fs-shadow-sm);
}
.logo-text {
  font-size: 20px; font-weight: 800; letter-spacing: -0.3px;
  background: var(--fs-grad-text);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
}
.nav-links { display: flex; gap: 36px; list-style: none; }
.nav-links a { color: #475569; text-decoration: none; font-size: 15px; font-weight: 500; transition: color .3s; }
.nav-links a:hover, .nav-links a.is-active { color: var(--fs-primary); }
.nav-actions { display: flex; align-items: center; gap: 16px; }

/* ===== 语言分段控件（PRD 5.3-1） ===== */
.lang-switch {
  display: inline-flex;
  align-items: center;
  gap: 2px;
  background: #f1f5f9;
  border-radius: var(--fs-radius-pill);
  padding: 4px;
}
.lang-seg {
  border: none;
  background: transparent;
  color: var(--fs-muted);
  font-size: 13px;
  font-weight: 600;
  padding: 6px 16px;
  border-radius: var(--fs-radius-pill);
  cursor: pointer;
  transition: .3s;
}
.lang-seg:hover { color: var(--fs-primary); }
.lang-seg.is-active {
  background: var(--fs-grad);
  color: #fff;
  box-shadow: var(--fs-shadow-sm);
}

/* ===== 按钮 ===== */
.btn-grad {
  background: var(--fs-grad);
  color: #fff;
  padding: 16px 36px;
  border-radius: var(--fs-radius-pill);
  font-weight: 600;
  font-size: 15px;
  border: none;
  cursor: pointer;
  transition: .3s;
  box-shadow: 0 8px 24px rgba(59, 130, 246, 0.3);
  text-decoration: none;
  display: inline-flex; align-items: center; gap: 8px; justify-content: center;
}
.btn-grad:hover { transform: translateY(-2px); box-shadow: var(--fs-shadow-lg); }
.btn-light {
  background: #fff;
  color: var(--fs-primary);
  padding: 16px 36px;
  border-radius: var(--fs-radius-pill);
  font-weight: 600;
  font-size: 15px;
  border: 1px solid rgba(59, 130, 246, 0.2);
  cursor: pointer;
  transition: .3s;
  text-decoration: none;
  display: inline-flex; align-items: center; gap: 8px; justify-content: center;
}
.btn-light:hover { border-color: var(--fs-primary); background: var(--fs-bg); transform: translateY(-2px); }
.nav-cta {
  background: var(--fs-grad);
  color: #fff;
  padding: 11px 28px;
  border-radius: var(--fs-radius-pill);
  font-weight: 600;
  font-size: 14px;
  cursor: pointer;
  border: none;
  transition: .3s;
  box-shadow: var(--fs-shadow-sm);
}
.nav-cta:hover { transform: translateY(-1px); box-shadow: var(--fs-shadow-lg); }
.fs-btn-ghost {
  background: transparent;
  border: 1px solid rgba(59, 130, 246, 0.3);
  color: var(--fs-primary);
  padding: 8px 16px;
  border-radius: var(--fs-radius-pill);
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: .3s;
}
.fs-btn-ghost:hover { background: rgba(59, 130, 246, 0.08); }

/* ===== 玻璃卡 ===== */
.fs-glass, .hero-glass {
  background: rgba(255, 255, 255, 0.6);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid rgba(255, 255, 255, 0.8);
  border-radius: var(--fs-radius);
  box-shadow: var(--fs-shadow);
  overflow: hidden;
}
.fs-glass-dark {
  background: rgba(255, 255, 255, 0.04);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--fs-radius);
}

/* ===== 区块与区块头 ===== */
.section { padding: 100px 40px; max-width: var(--fs-maxw); margin: 0 auto; }
.section-header { text-align: center; margin-bottom: 60px; }
.section-pill {
  display: inline-flex; align-items: center; gap: 6px;
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.08), rgba(6, 182, 212, 0.08));
  color: var(--fs-primary);
  padding: 8px 20px;
  border-radius: 30px;
  font-size: 13px;
  font-weight: 600;
  margin-bottom: 16px;
}
.section h2 {
  font-size: 44px;
  font-weight: 800;
  letter-spacing: -1px;
  background: linear-gradient(135deg, #0f172a, #334155);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
}
.section-sub { color: var(--fs-muted); font-size: 17px; margin-top: 12px; }

/* 深色区（Why Choose Us）变体 */
.why-us { background: linear-gradient(135deg, var(--fs-dark), var(--fs-dark-2)); position: relative; overflow: hidden; }
.why-us::before {
  content: '';
  position: absolute; inset: 0;
  background-image:
    radial-gradient(circle at 20% 50%, rgba(59, 130, 246, 0.1), transparent 50%),
    radial-gradient(circle at 80% 30%, rgba(6, 182, 212, 0.08), transparent 50%);
}
.why-us .section-pill { background: rgba(59, 130, 246, 0.15); color: #60a5fa; }
.why-us h2 {
  background: linear-gradient(135deg, #fff, #93c5fd);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
}
.why-us .section-sub { color: var(--fs-muted-2); }

/* ===== 页脚 ===== */
.footer { background: var(--fs-dark); padding: 70px 40px 30px; }
.footer-inner {
  max-width: var(--fs-maxw);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
}
.footer-brand .logo { margin-bottom: 16px; }
.footer-brand p { color: var(--fs-muted); font-size: 14px; line-height: 1.7; max-width: 300px; }
.footer-col h4 { color: #fff; font-size: 15px; font-weight: 600; margin-bottom: 16px; }
.footer-col a { display: block; color: var(--fs-muted); font-size: 14px; text-decoration: none; margin-bottom: 10px; transition: .3s; }
.footer-col a:hover { color: #60a5fa; }
.footer-bottom {
  max-width: var(--fs-maxw);
  margin: 40px auto 0;
  padding-top: 24px;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  text-align: center;
  color: #475569;
  font-size: 13px;
}

/* ===== 图标容器公共尺寸（SVG 继承 currentColor） ===== */
.cat-icon {
  width: 76px; height: 76px; margin: 0 auto 20px;
  border-radius: var(--fs-radius);
  display: flex; align-items: center; justify-content: center;
  color: var(--fs-primary);
  transition: .4s;
}
.cat-icon .icon { width: 36px; height: 36px; }
.stat-orb {
  width: 56px; height: 56px; border-radius: var(--fs-radius-sm);
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
  color: var(--fs-primary);
}
.stat-orb .icon { width: 28px; height: 28px; }
.why-icon {
  width: 56px; height: 56px; border-radius: var(--fs-radius-sm);
  display: flex; align-items: center; justify-content: center;
  margin-bottom: 20px;
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.15), rgba(6, 182, 212, 0.15));
  color: var(--fs-primary-light);
}
.why-icon .icon { width: 28px; height: 28px; }
.icon { display: inline-block; vertical-align: middle; }

/* 分类卡图标渐变底色（沿用设计稿 c1~c5） */
.cat-icon.c1 { background: linear-gradient(135deg, #dbeafe, #bfdbfe); }
.cat-icon.c2 { background: linear-gradient(135deg, #fef3c7, #fde68a); }
.cat-icon.c3 { background: linear-gradient(135deg, #d1fae5, #a7f3d0); }
.cat-icon.c4 { background: linear-gradient(135deg, #fce7f3, #fbcfe8); }
.cat-icon.c5 { background: linear-gradient(135deg, #e9d5ff, #d8b4fe); }
.cat-icon img { width: 100%; height: 100%; object-fit: contain; border-radius: var(--fs-radius); }

/* 数据条 orb 底色 */
.stat-orb.blue { background: linear-gradient(135deg, #dbeafe, #bfdbfe); }
.stat-orb.cyan { background: linear-gradient(135deg, #cffafe, #a5f3fc); color: var(--fs-accent); }
.stat-orb.indigo { background: linear-gradient(135deg, #e0e7ff, #c7d2fe); }
.stat-orb.sky { background: linear-gradient(135deg, #e0f2fe, #bae6fd); }

/* ===== 响应式断点（PRD 5.3-6 基础适配） ===== */
@media (max-width: 1024px) {
  .nav-links { display: none; }
  .section { padding: 72px 24px; }
  .section h2 { font-size: 34px; }
  .footer-inner { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
  .nav-inner { padding: 12px 20px; }
  .nav-cta { display: none; }
  .section { padding: 56px 20px; }
  .section h2 { font-size: 28px; }
  .section-sub { font-size: 15px; }
  .footer { padding: 48px 20px 24px; }
  .footer-inner { grid-template-columns: 1fr; gap: 28px; }
  .btn-grad, .btn-light { padding: 14px 26px; font-size: 14px; }
}

/* ===== 公共页面布局（列表 / 详情 / 联系 / 404 复用） ===== */
.page { padding: 120px 40px 80px; max-width: var(--fs-maxw); margin: 0 auto; min-height: 60vh; }
.page-head { margin-bottom: 36px; }
.page-head h1 { font-size: 40px; font-weight: 800; letter-spacing: -1px; color: var(--fs-text-strong); }
.back-link { display: inline-flex; align-items: center; gap: 6px; color: var(--fs-muted); font-size: 14px; text-decoration: none; margin-bottom: 24px; transition: .3s; }
.back-link:hover { color: var(--fs-primary); }

@media (max-width: 768px) {
  .page { padding: 96px 20px 56px; }
  .page-head h1 { font-size: 28px; }
}