html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: Arial, sans-serif;
  color: #1F2D3D;
  background-color: #F4F7FB;
  line-height: 1.6;
}

:root {
  --primary-color: #2F6BFF;
  --secondary-color: #6FA3FF;
  --text-main-color: #1F2D3D;
  --card-bg-color: #FFFFFF;
  --background-color: #F4F7FB;
  --border-color: #D6E2FF;
  --glow-color: #A5C4FF;
  --header-offset: 122px; /* 68px (header-top) + 52px (main-nav) */
}

body { padding-top: var(--header-offset); }

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  width: 100%;
  z-index: 1000;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  box-sizing: border-box;
}

.header-top {
  background-color: var(--primary-color); /* Deep blue for top bar */
  min-height: 68px;
  height: 68px;
  display: flex;
  align-items: center;
  overflow: hidden;
  box-sizing: border-box;
  width: 100%;
  padding: 0 20px; /* Add padding to the top bar itself */
}

.header-container {
  width: 100%;
  height: 100%;
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  /* Removed padding-left/right here as it's on header-top */
}

.logo {
  color: var(--card-bg-color); /* White text for logo */
  font-size: 24px;
  font-weight: bold;
  text-decoration: none;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 250px; /* Limit logo width */
  display: flex;
  align-items: center;
}

.logo img {
  display: block;
  max-height: 60px;
  height: auto;
  width: auto;
  max-width: 280px;
  object-fit: contain;
}

.desktop-nav-buttons {
  display: flex;
  gap: 12px;
  align-items: center;
}

.btn {
  padding: 10px 20px;
  border-radius: 8px;
  text-decoration: none;
  font-weight: bold;
  text-align: center;
  white-space: nowrap;
  transition: all 0.3s ease;
  border: none;
  cursor: pointer;
  color: var(--card-bg-color);
}

.btn-primary {
  background: linear-gradient(180deg, #4A8BFF 0%, #2F6BFF 100%);
  box-shadow: 0 4px 10px rgba(47, 107, 255, 0.3);
}

.btn-primary:hover {
  background: linear-gradient(180deg, #2F6BFF 0%, #4A8BFF 100%);
  box-shadow: 0 6px 15px rgba(47, 107, 255, 0.4);
}

.btn-secondary {
  background-color: var(--secondary-color); /* Lighter blue for secondary button */
  box-shadow: 0 4px 10px rgba(111, 163, 255, 0.3);
}

.btn-secondary:hover {
  background-color: #5b92e7; /* Slightly darker hover */
  box-shadow: 0 6px 15px rgba(111, 163, 255, 0.4);
}

.mobile-nav-buttons {
  box-sizing: border-box;
  display: none; /* Hidden by default on desktop */
  min-height: 48px; /* Placeholder height */
  background-color: #e0e7f2; /* A light background for mobile buttons */
  width: 100%;
  padding: 0 15px;
  justify-content: center;
  align-items: center;
  gap: 10px;
}

.main-nav {
  background-color: #F4F7FB; /* Light grey for navigation bar, different from top bar */
  min-height: 52px;
  height: 52px;
  display: flex;
  align-items: center;
  overflow: hidden;
  box-sizing: border-box;
  width: 100%;
  padding: 0 20px; /* Add padding to the nav bar itself */
}

.nav-container {
  width: 100%;
  height: 100%;
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  flex-direction: row;
  justify-content: center;
  align-items: center;
  gap: 25px;
}

.nav-link {
  color: var(--text-main-color);
  text-decoration: none;
  font-weight: bold;
  padding: 5px 0;
  white-space: nowrap;
  transition: color 0.3s ease;
}

.nav-link:hover,
.nav-link.active {
  color: var(--primary-color);
}

.hamburger-menu {
  display: none; /* Hidden by default on desktop */
  background: none;
  border: none;
  cursor: pointer;
  padding: 10px;
  position: relative;
  z-index: 1001;
}

.hamburger-menu .bar {
  display: block;
  width: 25px;
  height: 3px;
  background-color: var(--card-bg-color);
  margin: 5px 0;
  transition: all 0.3s ease;
}

.overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5);
  z-index: 999;
}

/* Footer styles */
.site-footer {
  background-color: var(--background-color);
  padding: 40px 20px 20px;
  color: var(--text-main-color);
  border-top: 1px solid var(--border-color);
  box-sizing: border-box;
}

.footer-top-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 30px;
  max-width: 1200px;
  margin: 0 auto 30px;
}

.footer-col {
  margin-bottom: 20px;
}

.footer-logo {
  color: var(--primary-color);
  font-size: 22px;
  font-weight: bold;
  text-decoration: none;
  display: block;
  margin-bottom: 15px;
}

.footer-description {
  font-size: 14px;
  line-height: 1.8;
  color: #4A5568;
  word-wrap: break-word;
  overflow-wrap: break-word;
}

.footer-heading {
  font-size: 18px;
  color: var(--text-main-color);
  margin-bottom: 15px;
}

.footer-nav {
  list-style: none;
  padding: 0;
  margin: 0;
}

.footer-nav li {
  margin-bottom: 8px;
}

.footer-nav a {
  color: #4A5568;
  text-decoration: none;
  font-size: 14px;
  transition: color 0.3s ease;
}

.footer-nav a:hover {
  color: var(--primary-color);
}

.footer-bottom {
  text-align: center;
  padding-top: 20px;
  border-top: 1px solid var(--border-color);
  font-size: 13px;
  color: #6B7280;
  max-width: 1200px;
  margin: 0 auto;
}

/* Mobile styles */
@media (max-width: 768px) {
  :root {
    --header-offset: 148px; /* 60px (header-top) + 48px (mobile-nav-buttons) + 48px (main-nav) = 156. Adjusted to 148px for a small buffer. */
  }
  body { padding-top: var(--header-offset); }

  .site-header {
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
  }

  .header-top {
    min-height: 60px !important;
    height: 60px !important;
    padding: 0 15px; /* Smaller padding for mobile */
  }

  .header-container {
    max-width: none;
    position: relative; /* For absolute positioning of logo if needed */
    justify-content: flex-start; /* Reset flex for mobile */
  }

  .hamburger-menu {
    display: block;
    order: 0; /* Place hamburger first */
    margin-right: auto; /* Push logo to center */
    padding-left: 0; /* Remove padding if any */
  }

  .hamburger-menu.active .bar:nth-child(1) {
    transform: translateY(8px) rotate(45deg);
  }
  .hamburger-menu.active .bar:nth-child(2) {
    opacity: 0;
  }
  .hamburger-menu.active .bar:nth-child(3) {
    transform: translateY(-8px) rotate(-45deg);
  }

  .logo {
    flex: 1 !important;
    display: flex !important;
    justify-content: center !important;
    align-items: center !important;
    max-width: calc(100% - 70px); /* Account for hamburger width */
    position: absolute; /* Absolute positioning for precise centering */
    left: 50%;
    transform: translateX(-50%);
  }
  .logo img {
    max-height: 56px !important;
  }

  .desktop-nav-buttons {
    display: none !important;
  }

  .mobile-nav-buttons {
    display: flex !important;
    min-height: 48px;
    align-items: center;
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
    padding: 8px 15px; /* Adjusted padding for mobile buttons */
    overflow: hidden;
    gap: 10px;
    flex-wrap: nowrap;
    background-color: #e0e7f2;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05);
  }
  .mobile-nav-buttons .btn {
    flex: 1; min-width: 0;
    max-width: calc(50% - 5px);
    box-sizing: border-box;
    padding: 8px 12px;
    font-size: 13px;
    white-space: normal;
    word-wrap: break-word;
    overflow-wrap: break-word;
  }

  .main-nav {
    display: none; /* Hidden by default, shown by JS */
    flex-direction: column;
    position: fixed;
    top: var(--header-offset); /* Position below fixed header and mobile buttons */
    left: 0;
    width: 280px;
    height: calc(100% - var(--header-offset));
    background-color: var(--card-bg-color); /* White background for mobile menu */
    box-shadow: 2px 0 10px rgba(0, 0, 0, 0.2);
    transform: translateX(-100%); /* Off-screen by default */
    transition: transform 0.3s ease-out;
    overflow-y: auto;
    align-items: flex-start;
    padding: 20px 0;
  }

  .main-nav.active {
    display: flex; /* Ensure it's visible when active */
    transform: translateX(0); /* Slide into view */
  }

  .nav-container {
    flex-direction: column;
    align-items: flex-start;
    gap: 15px;
    padding: 0 20px;
    width: 100%;
    max-width: none;
  }

  .nav-link {
    width: 100%;
    padding: 10px 0;
    border-bottom: 1px solid var(--border-color);
  }

  .nav-link:last-child {
    border-bottom: none;
  }

  .overlay.active {
    display: block;
  }

  .footer-top-grid {
    grid-template-columns: 1fr;
    gap: 20px;
  }
  .footer-col:last-child { margin-bottom: 0; }

  .page-content img {
    max-width: 100% !important;
    height: auto !important;
    display: block;
  }
  .page-content {
    overflow-x: hidden;
    max-width: 100%;
  }
  body {
    overflow-x: hidden;
  }
}
/* 移动端内容区防溢出（系统追加，请勿删除） */
@media (max-width: 768px) {
  .page-content img {
    max-width: 100% !important;
    height: auto !important;
    display: block;
  }
  .page-content {
    overflow-x: hidden;
    max-width: 100%;
  }
  body {
    overflow-x: hidden;
  }
}