/* ===================================================
   南京思后行官网 - 公共样式库 v1.0
   设计规范：极简白色现代风（方案三）
   =================================================== */

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

:root {
  --bg: #FAFAFA;
  --white: #FFFFFF;
  --text: #0F1923;
  --text2: #3D4F60;
  --muted: #8A9BB0;
  --accent: #1A56DB;
  --accent2: #0EA5E9;
  --accent-light: #EEF4FF;
  --border: #E5EAF0;
  --border2: #D0D9E4;
  --success: #10B981;
  --success-bg: #ECFDF5;
  --dark-grad: linear-gradient(135deg, #0F1923 0%, #1A2B4A 100%);
}

html { scroll-behavior: smooth; }

body {
  font-family: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  overflow-x: hidden;
}

/* ===== NAVIGATION ===== */
nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  height: 68px;
  display: flex; align-items: center;
}
.nav-inner {
  max-width: 1280px; margin: 0 auto; padding: 0 60px;
  width: 100%;
  display: flex; align-items: center; justify-content: space-between;
}
.logo { display: flex; align-items: center; gap: 12px; text-decoration: none; }
.logo-mark {
  width: 36px; height: 36px;
  background: var(--accent);
  border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  color: white; font-size: 16px; font-weight: 700;
  flex-shrink: 0;
}
.logo-name { font-size: 16px; font-weight: 600; color: var(--text); letter-spacing: 0.5px; }
.logo-sub { font-size: 10px; color: var(--muted); letter-spacing: 1.5px; text-transform: uppercase; margin-top: 1px; }

.nav-menu { display: flex; gap: 4px; list-style: none; }
.nav-menu > li { position: relative; }
.nav-menu > li > a {
  color: var(--text2); text-decoration: none;
  font-size: 14px; font-weight: 400;
  padding: 8px 14px; border-radius: 6px;
  display: flex; align-items: center; gap: 4px;
  transition: color 0.2s, background 0.2s;
}
.nav-menu > li > a:hover,
.nav-menu > li > a.active { color: var(--accent); background: var(--accent-light); }

/* Dropdown */
.nav-dropdown {
  position: absolute; top: calc(100% + 8px); left: 0;
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 8px;
  min-width: 200px;
  box-shadow: 0 16px 48px rgba(15,25,35,0.12);
  opacity: 0; visibility: hidden;
  transform: translateY(-8px);
  transition: all 0.2s;
  z-index: 100;
}
.nav-menu > li:hover .nav-dropdown {
  opacity: 1; visibility: visible; transform: translateY(0);
}
.nav-dropdown a {
  display: block; padding: 8px 12px;
  color: var(--text2); text-decoration: none;
  font-size: 13px; border-radius: 6px;
  transition: all 0.15s;
}
.nav-dropdown a:hover { background: var(--accent-light); color: var(--accent); }
.nav-dropdown-section { padding: 4px 12px 8px; font-size: 11px; color: var(--muted); font-weight: 500; letter-spacing: 0.5px; text-transform: uppercase; margin-top: 4px; }

/* Mega Dropdown (Products) */
.nav-mega-dropdown {
  position: absolute; top: calc(100% + 8px); left: 50%;
  transform: translateX(-50%) translateY(-8px);
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px 12px;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0 8px;
  box-shadow: 0 16px 48px rgba(15,25,35,0.12);
  opacity: 0; visibility: hidden;
  transition: all 0.2s;
  z-index: 100;
}
.nav-menu > li:hover .nav-mega-dropdown {
  opacity: 1; visibility: visible; transform: translateX(-50%) translateY(0);
}
.nav-mega-col { padding: 0 4px; }
.nav-mega-col + .nav-mega-col { border-left: 1px solid var(--border); padding-left: 12px; }
.nav-mega-dropdown a {
  display: block; padding: 7px 10px;
  color: var(--text2); text-decoration: none;
  font-size: 13px; border-radius: 6px;
  transition: all 0.15s; white-space: nowrap;
}
.nav-mega-dropdown a:hover { background: var(--accent-light); color: var(--accent); }
.nav-mega-dropdown .nav-dropdown-section {
  padding: 4px 10px 8px; font-size: 11px; color: var(--muted);
  font-weight: 500; letter-spacing: 0.5px; text-transform: uppercase;
  border-bottom: 1px solid var(--border); margin-bottom: 6px;
}
.nav-hot-tag {
  display: inline-block; font-size: 10px; font-weight: 600; padding: 1px 6px;
  border-radius: 4px; margin-left: 6px; vertical-align: middle; line-height: 1.4;
}
.nav-hot-tag.hot { background: #FEE2E2; color: #DC2626; }
.nav-hot-tag.new { background: #EEF2FF; color: #6366F1; }
.nav-hot-tag.ai { background: #F0FDF4; color: #059669; }
.nav-dropdown .nav-hot-tag { margin-left: 4px; }

.nav-actions { display: flex; gap: 12px; align-items: center; }
.btn-sm-outline {
  border: 1px solid var(--border2);
  color: var(--text2); padding: 7px 20px;
  border-radius: 6px; text-decoration: none;
  font-size: 13px; transition: all 0.2s;
}
.btn-sm-outline:hover { border-color: var(--accent); color: var(--accent); }
.btn-sm-fill {
  background: var(--accent);
  color: white; padding: 7px 20px;
  border-radius: 6px; text-decoration: none;
  font-size: 13px; font-weight: 500;
  transition: background 0.2s;
}
.btn-sm-fill:hover { background: #1447C0; }

/* Chevron SVG for dropdown indicator */
.nav-chevron { width: 12px; height: 12px; transition: transform 0.2s; }
.nav-menu > li:hover .nav-chevron { transform: rotate(180deg); }

/* ===== FOOTER ===== */
footer {
  background: var(--text);
  border-top: 1px solid rgba(255,255,255,0.06);
  padding: 72px 0 32px;
}
.footer-grid {
  max-width: 1280px; margin: 0 auto; padding: 0 60px;
  display: grid; grid-template-columns: 2.5fr 1fr 1fr 1fr 1fr;
  gap: 48px; margin-bottom: 56px;
}
.footer-brand-area {}
.footer-logo { display: flex; align-items: center; gap: 10px; margin-bottom: 16px; }
.footer-logo-mark { width: 36px; height: 36px; background: var(--accent); border-radius: 8px; display: flex; align-items: center; justify-content: center; color: white; font-size: 16px; font-weight: 700; }
.footer-brand-name { font-size: 15px; font-weight: 600; color: white; }
.footer-brand-sub { font-size: 10px; color: rgba(255,255,255,0.3); letter-spacing: 1.5px; text-transform: uppercase; }
.footer-desc { font-size: 13px; color: rgba(255,255,255,0.35); line-height: 1.8; font-weight: 300; margin-bottom: 24px; }
.footer-contact-item { display: flex; align-items: center; gap: 8px; font-size: 12px; color: rgba(255,255,255,0.35); margin-bottom: 8px; }
.footer-contact-item svg { flex-shrink: 0; opacity: 0.5; }

.footer-col h4 { font-size: 12px; font-weight: 600; color: rgba(255,255,255,0.6); margin-bottom: 20px; letter-spacing: 0.8px; text-transform: uppercase; }
.footer-links { list-style: none; display: flex; flex-direction: column; gap: 10px; }
.footer-links a { color: rgba(255,255,255,0.35); text-decoration: none; font-size: 13px; transition: color 0.2s; }
.footer-links a:hover { color: rgba(255,255,255,0.7); }

.footer-bottom {
  max-width: 1280px; margin: 0 auto; padding: 0 60px;
  border-top: 1px solid rgba(255,255,255,0.06);
  padding-top: 28px;
  display: flex; justify-content: space-between; align-items: center;
}
.footer-copy { font-size: 12px; color: rgba(255,255,255,0.2); }
.footer-icp { font-size: 12px; color: rgba(255,255,255,0.2); }
.footer-icp a { color: rgba(255,255,255,0.25); text-decoration: none; }

/* ===== LAYOUT UTILITIES ===== */
.container { max-width: 1280px; margin: 0 auto; padding: 0 60px; }

.section-eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  color: var(--accent); font-size: 12px; font-weight: 500;
  letter-spacing: 1px; text-transform: uppercase;
  margin-bottom: 16px;
}
.section-eyebrow::before { content: ''; width: 24px; height: 2px; background: var(--accent); flex-shrink: 0; }

.section-h2 { font-size: 40px; font-weight: 700; color: var(--text); line-height: 1.3; margin-bottom: 12px; }
.section-h2 em { font-style: normal; color: var(--accent); }
.section-p { font-size: 16px; color: var(--text2); max-width: 560px; line-height: 1.8; font-weight: 300; }

/* ===== BUTTONS ===== */
.btn-primary {
  background: var(--accent); color: white;
  padding: 13px 32px; border-radius: 8px; text-decoration: none;
  font-size: 14px; font-weight: 500; display: inline-flex; align-items: center; gap: 8px;
  transition: background 0.2s, transform 0.2s;
  box-shadow: 0 4px 16px rgba(26,86,219,0.25);
}
.btn-primary:hover { background: #1447C0; transform: translateY(-1px); }
.btn-secondary {
  background: var(--white); border: 1px solid var(--border2);
  color: var(--text2); padding: 13px 32px;
  border-radius: 8px; text-decoration: none;
  font-size: 14px; font-weight: 400; display: inline-flex; align-items: center; gap: 8px;
  transition: all 0.2s;
}
.btn-secondary:hover { border-color: var(--accent); color: var(--accent); }
.btn-white { background: white; color: var(--text); padding: 14px 40px; border-radius: 8px; text-decoration: none; font-size: 15px; font-weight: 600; transition: opacity 0.2s; display: inline-block; }
.btn-white:hover { opacity: 0.9; }
.btn-outline-white { border: 1px solid rgba(255,255,255,0.3); color: white; padding: 14px 40px; border-radius: 8px; text-decoration: none; font-size: 15px; transition: all 0.2s; display: inline-block; }
.btn-outline-white:hover { border-color: white; background: rgba(255,255,255,0.08); }

/* ===== CTA SECTION ===== */
.cta-section {
  padding: 100px 0;
  background: var(--dark-grad);
  text-align: center;
}
.cta-h2 { font-size: 44px; font-weight: 700; color: white; margin-bottom: 16px; }
.cta-h2 em { font-style: normal; color: var(--accent2); }
.cta-p { font-size: 17px; color: rgba(255,255,255,0.55); margin-bottom: 40px; font-weight: 300; }
.cta-btns { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }

/* ===== PAGE HEADER ===== */
.page-header {
  padding: 120px 0 60px;
  background: var(--white);
  border-bottom: 1px solid var(--border);
}
.breadcrumb { display: flex; align-items: center; gap: 8px; font-size: 13px; color: var(--muted); margin-bottom: 20px; }
.breadcrumb a { color: var(--accent); text-decoration: none; }
.breadcrumb a:hover { text-decoration: underline; }
.breadcrumb-sep { color: var(--border2); }
.page-h1 { font-size: 48px; font-weight: 700; color: var(--text); margin-bottom: 16px; line-height: 1.2; }
.page-h1 em { font-style: normal; color: var(--accent); }
.page-desc { font-size: 16px; color: var(--text2); max-width: 680px; line-height: 1.8; font-weight: 300; }

/* ===== CARD COMPONENTS ===== */
.card-base {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: 16px;
  transition: all 0.3s;
}
.card-base:hover {
  border-color: var(--accent);
  box-shadow: 0 12px 40px rgba(26,86,219,0.1);
  transform: translateY(-4px);
}

/* Icon container */
.icon-box {
  border-radius: 12px;
  background: var(--accent-light);
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
}
.icon-box-sm { width: 40px; height: 40px; border-radius: 10px; }
.icon-box-md { width: 52px; height: 52px; border-radius: 12px; }
.icon-box-lg { width: 64px; height: 64px; border-radius: 14px; }

/* Tag / Badge */
.tag { display: inline-block; padding: 3px 10px; border-radius: 4px; font-size: 11px; font-weight: 500; }
.tag-blue { background: var(--accent-light); color: var(--accent); }
.tag-green { background: var(--success-bg); color: var(--success); }
.tag-gray { background: var(--bg); border: 1px solid var(--border); color: var(--text2); }

/* Stats bar */
.stats-bar { background: var(--text); }
.stats-inner {
  max-width: 1280px; margin: 0 auto; padding: 0 60px;
  display: grid; grid-template-columns: repeat(4, 1fr);
}
.stat-cell {
  padding: 40px 32px;
  border-right: 1px solid rgba(255,255,255,0.08);
  text-align: center;
}
.stat-cell:last-child { border-right: none; }
.stat-num { font-size: 40px; font-weight: 700; color: white; line-height: 1; }
.stat-num span { font-size: 20px; }
.stat-label { font-size: 13px; color: rgba(255,255,255,0.4); margin-top: 8px; }

/* Checklist */
.check-list { list-style: none; display: flex; flex-direction: column; gap: 10px; }
.check-list li { display: flex; align-items: flex-start; gap: 10px; font-size: 14px; color: var(--text2); line-height: 1.6; }
.check-list li::before { content: ''; width: 18px; height: 18px; background: var(--accent-light); border-radius: 50%; flex-shrink: 0; margin-top: 1px; display: flex; align-items: center; justify-content: center; }

/* Divider */
.divider { height: 1px; background: var(--border); margin: 0; }

/* ===================================================
   MOBILE RESPONSIVE — 只在 768px 以下生效
   =================================================== */
@media (max-width: 768px) {
  /* --- Navigation --- */
  .nav-inner { padding: 0 20px; }
  .nav-toggle {
    display: flex !important;
    background: none; border: none; cursor: pointer; padding: 8px;
    color: var(--text2);
  }
  .nav-menu {
    display: none;
    position: fixed; top: 68px; left: 0; right: 0; bottom: 0;
    background: rgba(255,255,255,0.98);
    backdrop-filter: blur(20px);
    flex-direction: column;
    padding: 16px 20px;
    gap: 0;
    overflow-y: auto;
    z-index: 999;
  }
  .nav-menu.open { display: flex; }
  .nav-menu > li { width: 100%; }
  .nav-menu > li > a {
    padding: 14px 0; font-size: 16px; border-bottom: 1px solid var(--border);
    border-radius: 0; justify-content: space-between;
  }
  .nav-menu > li > a.active { background: none; }
  .nav-menu > li:hover .nav-dropdown,
  .nav-menu > li:hover .nav-mega-dropdown { display: none; }
  /* On mobile, dropdowns are always visible inside the menu */
  .nav-menu.open .nav-dropdown,
  .nav-menu.open .nav-mega-dropdown {
    display: block; position: static; opacity: 1; visibility: visible;
    transform: none; box-shadow: none; border: none; border-radius: 0;
    padding: 0 0 8px 16px; min-width: 0; background: none;
  }
  .nav-menu.open .nav-mega-dropdown {
    display: grid; grid-template-columns: 1fr;
    gap: 0; padding: 0 0 8px 16px;
  }
  .nav-menu.open .nav-mega-col { padding: 8px 0; }
  .nav-menu.open .nav-mega-col + .nav-mega-col { border-left: none; border-top: 1px solid var(--border); padding-top: 12px; }
  .nav-menu.open .nav-dropdown a,
  .nav-menu.open .nav-mega-dropdown a { padding: 8px 0; font-size: 14px; white-space: normal; }
  .nav-menu.open .nav-dropdown-section { padding: 12px 0 6px; font-size: 11px; border-bottom: none; margin-bottom: 0; }
  .nav-menu.open .nav-hot-tag { margin-left: 4px; }
  .nav-actions { display: none; }
  .nav-menu.open > li:last-child .nav-cta { display: block; padding: 14px 0; font-size: 16px; text-align: center; background: var(--accent); color: white; border-radius: 8px; margin-top: 16px; }

  /* --- Container --- */
  .container { padding: 0 20px; }

  /* --- Typography --- */
  .section-h2 { font-size: 28px; }
  .page-h1 { font-size: 30px; }
  .cta-h2 { font-size: 28px; }
  .cta-p { font-size: 15px; }
  .section-p { font-size: 15px; max-width: 100%; }

  /* --- Stats bar --- */
  .stats-inner { padding: 0 20px; grid-template-columns: repeat(2, 1fr); }
  .stat-cell { padding: 24px 16px; }
  .stat-num { font-size: 28px; }

  /* --- Footer --- */
  .footer-grid { grid-template-columns: 1fr; padding: 0 20px; gap: 32px; }
  .footer-bottom { padding: 20px; flex-direction: column; gap: 8px; text-align: center; }
}