/* ===== Unified Header (extracted from index.html) =====
 * All selectors scoped under .site-header / .nav-menu / .nav-sub / .nav-toggle
 * to avoid conflicting with legacy base.css / head.css on old pages.
 */

.site-header {
  position: sticky; top: 0; left: 0; right: 0; z-index: 100;
  height: 80px;
  display: flex; align-items: center;
  background: #fff;
  box-shadow: 0 1px 8px rgba(0,0,0,0.08);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
}
.site-header *, .site-header *::before, .site-header *::after { box-sizing: border-box; }
.site-header a { text-decoration: none; color: inherit; }
.site-header ul, .site-header li { list-style: none; margin: 0; padding: 0; }
.site-header img { max-width: 100%; display: block; }

.header-inner {
  width: 100%; max-width: 1440px; margin: 0 auto;
  padding: 0 60px;
  display: flex; align-items: center; justify-content: space-between;
}

.site-header .logo { display: flex; align-items: center; }
.site-header .logo img { height: 50px; width: auto; }
.site-header .logo .logo-white { display: none; }
.site-header .logo .logo-dark { display: block; }

/* Nav container */
.nav-menu { display: flex; align-items: center; height: 80px; }
.nav-menu > ul {
  display: flex; list-style: none; margin: 0; padding: 0; height: 100%;
}
.nav-menu > ul > li {
  position: relative; height: 100%;
  display: flex; align-items: center;
  padding: 0 14px;
}
.nav-menu > ul > li > a {
  font-size: 15px; color: #333; font-weight: 400;
  transition: color 0.3s; position: relative;
  display: flex; align-items: center; height: 100%;
  white-space: nowrap;
}
/* Underline animation: expands from center */
.nav-menu > ul > li::after {
  content: ''; position: absolute; bottom: 0; left: 50%;
  width: 0; height: 2px; background: #CC0000;
  transition: width 0.4s, left 0.4s;
}
.nav-menu > ul > li:hover::after {
  width: 50px; left: calc(50% - 25px);
}
.nav-menu > ul > li:hover > a,
.nav-menu > ul > li.active > a { color: #CC0000; }

/* ===== Dropdown Submenus ===== */
.nav-sub {
  position: absolute; top: 80px; left: 50%;
  transform: translateX(-50%);
  min-width: 180px;
  background: #fff;
  box-shadow: 0 8px 30px rgba(0,0,0,0.12);
  border-radius: 0 0 6px 6px;
  overflow: hidden;
  max-height: 0; opacity: 0;
  transition: max-height 0.35s ease, opacity 0.25s ease;
  pointer-events: none;
}
.nav-menu > ul > li:hover > .nav-sub {
  max-height: 500px; opacity: 1;
  pointer-events: auto;
}
.nav-sub a {
  display: block; padding: 10px 24px;
  font-size: 14px; color: #666;
  transition: background 0.2s, color 0.2s;
  white-space: nowrap;
}
.nav-sub a:hover {
  background: #CC0000; color: #fff;
}
.nav-sub.wide {
  min-width: 580px; display: flex; padding: 20px 30px; gap: 28px;
  left: 50%; transform: translateX(-50%);
}
.nav-sub.wide-lg { min-width: 720px; }
.nav-sub.wide .sub-col { flex: 1; }
.nav-sub.wide .sub-col-title {
  font-size: 13px; font-weight: 700; color: #CC0000;
  padding-bottom: 7px; margin-bottom: 6px;
  border-bottom: 2px solid #f0f0f0;
  letter-spacing: 0.04em;
}
.nav-sub.wide a { padding: 5px 0; font-size: 13px; }
.nav-sub.wide a:hover { background: none; color: #CC0000; }

/* Mobile nav toggle */
.nav-toggle {
  display: none; cursor: pointer; width: 44px; height: 44px;
  position: relative; z-index: 3;
}
.nav-toggle span {
  display: block; width: 24px; height: 2px; background: #333;
  position: absolute; left: 10px;
  transition: all 0.4s;
}
.nav-toggle span:nth-child(1) { top: 13px; }
.nav-toggle span:nth-child(2) { top: 21px; }
.nav-toggle span:nth-child(3) { top: 29px; }
.nav-toggle.open span:nth-child(1) { top: 21px; transform: rotate(45deg); }
.nav-toggle.open span:nth-child(2) { opacity: 0; }
.nav-toggle.open span:nth-child(3) { top: 21px; transform: rotate(-45deg); }

@media (max-width: 1200px) {
  .header-inner { padding: 0 30px; }
}

@media (max-width: 768px) {
  .nav-menu { display: none; }
  .nav-toggle { display: block; }
  .nav-menu.open {
    display: block;
    position: absolute; top: 80px; left: 0; right: 0;
    background: #fff; height: auto;
    box-shadow: 0 8px 24px rgba(0,0,0,0.12);
  }
  .nav-menu.open > ul {
    flex-direction: column; height: auto;
  }
  .nav-menu.open > ul > li {
    height: auto; padding: 0;
    border-bottom: 1px solid #f0f0f0;
    flex-direction: column; align-items: stretch;
  }
  .nav-menu.open > ul > li > a {
    color: #333; padding: 14px 24px; height: auto;
  }
  .nav-menu.open > ul > li::after { display: none; }
  .nav-menu.open .nav-sub {
    position: static; transform: none;
    box-shadow: none; border-radius: 0;
    max-height: 0; opacity: 0;
    transition: max-height 0.3s ease, opacity 0.2s ease;
  }
  .nav-menu.open > ul > li.sub-open > .nav-sub {
    max-height: 800px; opacity: 1; pointer-events: auto;
  }
  .nav-menu.open .nav-sub a { padding: 10px 40px; }
  .nav-sub.wide,
  .nav-sub.wide-lg {
    min-width: unset; flex-direction: column; padding: 10px 24px; gap: 8px;
  }
}