/* ===== CSS Reset & Variables ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
:root {
  --primary: #1a3a6b;
  --primary-light: #2557a7;
  --accent: #e8a020;
  --accent-light: #f5c842;
  --dark: #0d1b2a;
  --text: #2c3e50;
  --text-muted: #6b7280;
  --bg-light: #f8fafc;
  --bg-section: #eef2f7;
  --white: #ffffff;
  --border: #dde3ec;
  --shadow: 0 4px 24px rgba(26,58,107,0.10);
  --shadow-hover: 0 8px 40px rgba(26,58,107,0.18);
  --radius: 12px;
  --radius-lg: 20px;
  --font: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', Arial, sans-serif;
}
html { scroll-behavior: smooth; }
body { font-family: var(--font); color: var(--text); background: var(--white); line-height: 1.7; }
a { text-decoration: none; color: inherit; }
img { max-width: 100%; display: block; }
ul { list-style: none; }

/* ===== Utility ===== */
.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }
.section-title { font-size: 2rem; font-weight: 700; color: var(--primary); text-align: center; margin-bottom: 12px; }
.section-subtitle { text-align: center; color: var(--text-muted); font-size: 1rem; margin-bottom: 48px; max-width: 600px; margin-left: auto; margin-right: auto; }
.tag { display: inline-block; background: var(--accent); color: var(--white); font-size: 0.78rem; font-weight: 600; padding: 3px 12px; border-radius: 20px; letter-spacing: 1px; margin-bottom: 14px; }
.btn { display: inline-block; padding: 12px 30px; border-radius: 50px; font-size: 0.95rem; font-weight: 600; cursor: pointer; transition: all .25s; border: none; font-family: var(--font); }
.btn-primary { background: linear-gradient(135deg, var(--primary-light), var(--primary)); color: var(--white); box-shadow: 0 4px 16px rgba(37,87,167,0.35); }
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(37,87,167,0.45); }
.btn-accent { background: linear-gradient(135deg, var(--accent), var(--accent-light)); color: var(--dark); font-weight: 700; }
.btn-accent:hover { transform: translateY(-2px); box-shadow: 0 6px 20px rgba(232,160,32,0.4); }
.btn-outline-white { background: transparent; color: var(--white); border: 2px solid rgba(255,255,255,0.7); }
.btn-outline-white:hover { background: rgba(255,255,255,0.15); }

/* ===== Navbar ===== */
.navbar {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: rgba(13,27,42,0.97); backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255,255,255,0.08);
}
.navbar .container { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.logo { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }
.logo-icon { width: 38px; height: 38px; border-radius: 10px; background: linear-gradient(135deg, var(--accent), var(--primary-light)); display: flex; align-items: center; justify-content: center; font-size: 1.2rem; font-weight: 900; color: var(--white); flex-shrink: 0; }
.logo-text { font-size: 1.2rem; font-weight: 700; color: var(--white); letter-spacing: 1px; }
.logo-sub { font-size: 0.65rem; color: rgba(255,255,255,0.45); letter-spacing: 1px; display: block; }
.nav-links { display: flex; align-items: center; gap: 28px; }
.nav-links a { color: rgba(255,255,255,0.82); font-size: 0.9rem; font-weight: 500; transition: color .2s; white-space: nowrap; }
.nav-links a:hover { color: var(--white); }
.nav-dropdown { position: relative; }
.nav-dropdown > a::after { content: ' ▾'; font-size: 0.7rem; }
/* 用 padding-top 填充导航链接与下拉菜单之间的间隙，防止鼠标移动时菜单消失 */
.dropdown-menu {
  display: none;
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  background: var(--dark);
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: var(--radius);
  padding: 8px 0;
  min-width: 180px;
  box-shadow: 0 8px 32px rgba(0,0,0,0.4);
  z-index: 100;
  /* 顶部留出透明缓冲区，防止鼠标在间隙处移动时菜单消失 */
  margin-top: 0;
}
/* 用伪元素在导航项与下拉菜单之间创建不可见的悬停桥接区域 */
.nav-dropdown::after {
  content: '';
  position: absolute;
  top: 100%;
  left: -20px;
  right: -20px;
  height: 20px;
  display: none;
}
.nav-dropdown:hover::after { display: block; }
.nav-dropdown > a { padding-bottom: 20px; margin-bottom: -20px; }
/* 下拉菜单由 JS 控制显示，不使用 CSS hover 触发 */
.dropdown-menu a { display: block; padding: 10px 20px; color: rgba(255,255,255,0.8); font-size: 0.88rem; transition: all .2s; white-space: nowrap; }
.dropdown-menu a:hover { background: rgba(255,255,255,0.08); color: var(--accent-light); }
.nav-cta { background: linear-gradient(135deg, var(--accent), var(--accent-light)); color: var(--dark) !important; padding: 8px 20px; border-radius: 50px; font-weight: 700 !important; }
.nav-cta:hover { transform: translateY(-1px); box-shadow: 0 4px 16px rgba(232,160,32,0.5); }

/* Hamburger */
.hamburger { display: none; flex-direction: column; gap: 5px; cursor: pointer; padding: 6px; background: none; border: none; }
.hamburger span { display: block; width: 22px; height: 2px; background: var(--white); border-radius: 2px; transition: all .3s; }
.hamburger.open span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* Mobile menu */
.mobile-menu { display: none; position: fixed; top: 64px; left: 0; right: 0; bottom: 0; background: rgba(13,27,42,0.99); padding: 16px 0; flex-direction: column; z-index: 999; overflow-y: auto; }
.mobile-menu.open { display: flex; }
.mobile-menu a { color: rgba(255,255,255,0.85); padding: 14px 24px; border-bottom: 1px solid rgba(255,255,255,0.06); font-size: 1rem; display: block; }
.mobile-menu a:hover { background: rgba(255,255,255,0.05); color: var(--accent-light); }
.mobile-menu .mobile-section-title { color: rgba(255,255,255,0.35); font-size: 0.75rem; padding: 16px 24px 6px; letter-spacing: 2px; font-weight: 600; }
.mobile-menu .mobile-cta { margin: 16px 24px; background: linear-gradient(135deg, var(--accent), var(--accent-light)); color: var(--dark) !important; text-align: center; border-radius: 50px; font-weight: 700; padding: 14px 24px; border-bottom: none !important; }

/* ===== Page Hero (inner pages) ===== */
.page-hero {
  padding: 120px 0 70px;
  background: linear-gradient(135deg, var(--dark) 0%, #0f2744 50%, #1a3a6b 100%);
  position: relative; overflow: hidden;
}
.page-hero::before {
  content: ''; position: absolute; top: -100px; right: -100px;
  width: 500px; height: 500px; border-radius: 50%;
  background: radial-gradient(circle, rgba(37,87,167,0.2) 0%, transparent 70%);
}
.page-hero-content { position: relative; z-index: 1; }
.page-hero-badge { display: inline-flex; align-items: center; gap: 8px; background: rgba(232,160,32,0.15); border: 1px solid rgba(232,160,32,0.4); color: var(--accent-light); padding: 5px 14px; border-radius: 50px; font-size: 0.82rem; font-weight: 600; margin-bottom: 20px; }
.page-hero h1 { font-size: 2.6rem; font-weight: 800; color: var(--white); line-height: 1.25; margin-bottom: 16px; }
.page-hero p { color: rgba(255,255,255,0.72); font-size: 1.05rem; line-height: 1.8; max-width: 600px; margin-bottom: 28px; }
.breadcrumb { display: flex; align-items: center; gap: 8px; font-size: 0.85rem; color: rgba(255,255,255,0.45); margin-bottom: 20px; }
.breadcrumb a { color: rgba(255,255,255,0.55); transition: color .2s; }
.breadcrumb a:hover { color: var(--accent-light); }
.breadcrumb span { color: rgba(255,255,255,0.25); }

/* ===== Footer ===== */
.footer { background: var(--dark); color: rgba(255,255,255,0.7); padding: 56px 0 0; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; padding-bottom: 40px; border-bottom: 1px solid rgba(255,255,255,0.1); }
.footer-brand p { margin-top: 14px; font-size: 0.87rem; line-height: 1.8; color: rgba(255,255,255,0.5); }
.footer-col h4 { color: var(--white); font-size: 0.92rem; font-weight: 700; margin-bottom: 18px; }
.footer-col ul { display: flex; flex-direction: column; gap: 10px; }
.footer-col ul li a { color: rgba(255,255,255,0.5); font-size: 0.87rem; transition: color .2s; }
.footer-col ul li a:hover { color: var(--accent-light); }
.footer-bottom { padding: 18px 0; text-align: center; font-size: 0.82rem; color: rgba(255,255,255,0.3); }

/* ===== Scroll to top ===== */
.scroll-top { position: fixed; bottom: 28px; right: 20px; z-index: 999; width: 44px; height: 44px; border-radius: 50%; background: linear-gradient(135deg, var(--primary-light), var(--primary)); color: var(--white); border: none; cursor: pointer; display: flex; align-items: center; justify-content: center; font-size: 1.1rem; box-shadow: 0 4px 16px rgba(37,87,167,0.4); opacity: 0; transition: all .3s; pointer-events: none; }
.scroll-top.visible { opacity: 1; pointer-events: all; }

/* ===== Animations ===== */
@keyframes fadeInUp { from { opacity: 0; transform: translateY(24px); } to { opacity: 1; transform: translateY(0); } }
.anim { opacity: 0; transform: translateY(24px); transition: opacity .6s ease, transform .6s ease; }
.anim.visible { opacity: 1; transform: translateY(0); }

/* ===== Responsive ===== */
@media (max-width: 1024px) {
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
}
@media (max-width: 768px) {
  .nav-links { display: none; }
  .hamburger { display: flex; }
  .section-title { font-size: 1.6rem; }
  .section-subtitle { font-size: 0.93rem; margin-bottom: 36px; }
  .page-hero { padding: 100px 0 50px; }
  .page-hero h1 { font-size: 1.9rem; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 28px; }
}
@media (max-width: 480px) {
  .container { padding: 0 16px; }
  .page-hero h1 { font-size: 1.6rem; }
  .footer-grid { grid-template-columns: 1fr; }
}