/* ============================================================
   东禾智能 官网原型 · 全局样式
   Donghe Intellectual · Global Stylesheet
   品牌蓝精确值从logo提取：#0175AE
============================================================ */

:root {
  --brand: #0175AE;
  --brand-dark: #005A85;
  --brand-light: #4FB3DB;
  --brand-ghost: rgba(1,117,174,0.08);
  --navy: #0B2545;
  --navy-deep: #050E1E;
  --ink: #0F172A;
  --grey-50: #F8FAFC;
  --grey-100: #F1F5F9;
  --grey-200: #E2E8F0;
  --grey-300: #CBD5E1;
  --grey-400: #94A3B8;
  --grey-500: #64748B;
  --grey-600: #475569;
  --white: #FFFFFF;
  --accent: #4FC3F7;
  --success: #22C55E;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', 'PingFang SC', 'Microsoft YaHei', -apple-system, sans-serif;
  color: var(--ink);
  background: var(--white);
  line-height: 1.6;
  overflow-x: hidden;
}

a { color: inherit; text-decoration: none; }

img { max-width: 100%; display: block; }

/* ============================================================
   顶部导航（共享）
============================================================ */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  padding: 18px 56px;
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 80px;  /* logo 和菜单之间的大间距 */
  background: rgba(255,255,255,0.78);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border-bottom: 1px solid rgba(15,23,42,0.06);
  transition: padding 0.3s ease, box-shadow 0.3s ease;
}
.nav.scrolled { padding: 10px 56px; box-shadow: 0 4px 24px rgba(0,0,0,0.05); }

.nav-logo { height: 116px; display: flex; align-items: center; transition: height 0.3s ease; }
.nav-logo img { height: 100%; width: auto; display: block; }
.nav.scrolled .nav-logo { height: 90px; }

.nav-menu {
  display: flex;
  gap: 44px;
  list-style: none;
  justify-content: center;
}
.nav-menu a {
  font-size: 14px;
  font-weight: 500;
  color: var(--ink);
  letter-spacing: 0.02em;
  position: relative;
  padding: 6px 0;
  transition: color 0.2s;
  white-space: nowrap;
}
.nav-menu a:hover, .nav-menu a.active { color: var(--brand); }
.nav-menu a::after {
  content: '';
  position: absolute;
  bottom: 0; left: 0;
  width: 0; height: 1.5px;
  background: var(--brand);
  transition: width 0.3s ease;
}
.nav-menu a:hover::after, .nav-menu a.active::after { width: 100%; }

.nav-right { display: flex; align-items: center; gap: 28px; }
.lang-switch {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  user-select: none;
}
.lang-switch .lang-btn {
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 4px 6px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--grey-500);
  font-weight: 500;
  transition: color 0.2s ease, transform 0.2s ease;
  border-radius: 2px;
}
.lang-switch .lang-btn:hover { color: var(--brand); }
.lang-switch .lang-btn.active { color: var(--brand); font-weight: 700; }
.lang-switch .lang-divider { color: var(--grey-300); font-family: 'JetBrains Mono', monospace; font-size: 12px; }
.nav-cta {
  padding: 11px 22px;
  background: var(--brand);
  color: var(--white);
  font-size: 13px;
  font-weight: 600;
  border-radius: 2px;
  letter-spacing: 0.05em;
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
  white-space: nowrap;
}
.nav-cta:hover {
  background: var(--brand-dark);
  transform: translateY(-1px);
  box-shadow: 0 8px 20px rgba(1,117,174,0.25);
}

/* ============================================================
   共享：按钮、标签、分割元素
============================================================ */
.btn-primary {
  padding: 18px 36px;
  background: var(--brand);
  color: var(--white);
  font-size: 15px;
  font-weight: 600;
  border-radius: 2px;
  display: inline-flex;
  align-items: center;
  gap: 12px;
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
  border: none;
  cursor: pointer;
}
.btn-primary::before {
  content: '';
  position: absolute;
  top: 0; left: -100%;
  width: 100%; height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
  transition: left 0.6s ease;
}
.btn-primary:hover::before { left: 100%; }
.btn-primary:hover {
  background: var(--brand-dark);
  transform: translateY(-2px);
  box-shadow: 0 12px 30px rgba(1,117,174,0.35);
}
.btn-primary .arrow { transition: transform 0.3s ease; }
.btn-primary:hover .arrow { transform: translateX(4px); }

.btn-secondary {
  padding: 18px 36px;
  background: transparent;
  color: var(--navy);
  font-size: 15px;
  font-weight: 600;
  border: 1px solid var(--navy);
  border-radius: 2px;
  display: inline-flex;
  align-items: center;
  gap: 12px;
  transition: all 0.3s ease;
  cursor: pointer;
}
.btn-secondary:hover { background: var(--navy); color: var(--white); }

.btn-ghost {
  padding: 10px 18px;
  background: transparent;
  color: var(--brand);
  font-size: 13px;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  letter-spacing: 0.02em;
  border-bottom: 1px solid transparent;
  transition: all 0.2s ease;
}
.btn-ghost:hover { border-bottom-color: var(--brand); gap: 12px; }

/* eyebrow: 小标签 */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.22em;
  color: var(--brand);
  text-transform: uppercase;
  margin-bottom: 28px;
}
.eyebrow::before {
  content: '';
  width: 40px;
  height: 1px;
  background: var(--brand);
}
.eyebrow.light { color: var(--brand-light); }
.eyebrow.light::before { background: var(--brand-light); }

/* section 通用标题 */
.section-head { margin-bottom: 64px; max-width: 900px; }
.section-head h2 {
  font-size: clamp(36px, 3.6vw, 52px);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.02em;
  color: var(--navy);
  margin-bottom: 20px;
}
.section-head p {
  font-size: 17px;
  color: var(--grey-500);
  max-width: 680px;
  line-height: 1.7;
}

/* ============================================================
   页面 Hero（非首页）
============================================================ */
.page-hero {
  padding: 160px 56px 100px;
  background: linear-gradient(135deg, #F0F7FB 0%, #E1EEF5 100%);
  position: relative;
  overflow: hidden;
}
.page-hero::after {
  content: '';
  position: absolute;
  top: 0; right: 0;
  width: 45%; height: 100%;
  background: linear-gradient(135deg, rgba(1,117,174,0.06), transparent 70%);
  clip-path: polygon(20% 0, 100% 0, 100% 100%, 0 100%);
}
.page-hero .eyebrow { color: var(--brand); }
.page-hero-content { max-width: 900px; position: relative; z-index: 2; }
.page-hero h1 {
  font-size: clamp(40px, 5vw, 72px);
  font-weight: 800;
  line-height: 1.08;
  letter-spacing: -0.03em;
  color: var(--navy);
  margin-bottom: 24px;
}
.page-hero h1 .highlight {
  color: var(--brand);
  position: relative;
}
.page-hero h1 .highlight::after {
  content: '';
  position: absolute;
  bottom: 4px; left: 0;
  width: 100%; height: 3px;
  background: var(--brand);
  opacity: 0.3;
}
.page-hero .lead {
  font-size: 20px;
  line-height: 1.7;
  color: var(--grey-600);
  margin-bottom: 16px;
}
.page-hero .lead-en {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 15px;
  color: var(--grey-400);
  font-style: italic;
  letter-spacing: 0.02em;
}

/* Breadcrumb */
.breadcrumb {
  display: flex;
  gap: 8px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--grey-500);
  margin-bottom: 32px;
}
.breadcrumb a:hover { color: var(--brand); }
.breadcrumb .sep { color: var(--grey-300); }

/* ============================================================
   容器与section
============================================================ */
.section { padding: 120px 56px; }
.section.dark { background: var(--navy); color: var(--white); }
.section.alt { background: var(--grey-50); }
.section-tight { padding: 80px 56px; }

.container { max-width: 1400px; margin: 0 auto; }

/* ============================================================
   卡片
============================================================ */
.card {
  background: var(--white);
  border: 1px solid var(--grey-200);
  padding: 32px;
  border-radius: 2px;
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
}
.card:hover {
  border-color: var(--brand);
  transform: translateY(-4px);
  box-shadow: 0 20px 40px rgba(1,117,174,0.12);
}
.card::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 0; height: 2px;
  background: var(--brand);
  transition: width 0.4s ease;
}
.card:hover::before { width: 100%; }

.card-num {
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px;
  letter-spacing: 0.15em;
  color: var(--brand);
  margin-bottom: 16px;
  font-weight: 700;
}
.card h3 {
  font-size: 22px;
  font-weight: 700;
  color: var(--navy);
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}
.card .subtitle {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 13px;
  color: var(--grey-400);
  margin-bottom: 16px;
  letter-spacing: 0.02em;
}
.card p { color: var(--grey-600); font-size: 14px; line-height: 1.7; }

/* ============================================================
   footer（共享）
============================================================ */
.footer {
  background: var(--navy-deep);
  color: var(--grey-400);
  padding: 80px 56px 32px;
}
.footer-top {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr 1fr;
  gap: 48px;
  padding-bottom: 48px;
  border-bottom: 1px solid rgba(255,255,255,0.08);
}
.footer-brand .logo-wrapper {
  height: 58px;
  margin-bottom: 28px;
  opacity: 0.98;
}
.footer-brand .logo-wrapper img { height: 100%; width: auto; display: block; }
.footer-brand p {
  font-size: 13px;
  line-height: 1.7;
  color: var(--grey-500);
  max-width: 320px;
}
.footer-col h4 {
  color: var(--white);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: 20px;
  font-family: 'JetBrains Mono', monospace;
}
.footer-col ul { list-style: none; }
.footer-col li { margin-bottom: 10px; }
.footer-col a {
  font-size: 13px;
  color: var(--grey-400);
  transition: color 0.2s;
}
.footer-col a:hover { color: var(--brand-light); }
.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 32px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px;
  color: var(--grey-500);
  letter-spacing: 0.05em;
}
.footer-bottom .brand-name { color: var(--white); font-weight: 700; letter-spacing: 0.15em; }

/* ============================================================
   动画
============================================================ */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.8s ease, transform 0.8s ease;
}
.fade-in.visible { opacity: 1; transform: translateY(0); }

.fade-in-delay-1 { transition-delay: 0.1s; }
.fade-in-delay-2 { transition-delay: 0.2s; }
.fade-in-delay-3 { transition-delay: 0.3s; }

/* ============================================================
   响应式
============================================================ */
@media (max-width: 1024px) {
  .nav { padding: 14px 24px; grid-template-columns: auto auto; gap: 16px; }
  .nav.scrolled { padding: 10px 24px; }
  .nav-logo { height: 78px; }
  .nav.scrolled .nav-logo { height: 62px; }
  .footer-brand .logo-wrapper { height: 52px; }
  .nav-menu { display: none; }
  .page-hero { padding: 120px 24px 60px; }
  .section { padding: 80px 24px; }
  .footer { padding: 60px 24px 24px; }
  .footer-top { grid-template-columns: 1fr 1fr; gap: 32px; }
  .footer-bottom { flex-direction: column; gap: 12px; text-align: center; }
}
@media (max-width: 640px) {
  .footer-top { grid-template-columns: 1fr; }
}