/* ===== CSS Variables ===== */
:root {
  --color-primary: #1D2088;
  --color-primary-dark: #0D1442;
  --color-accent: #00E5FF;
  --color-accent-hover: #00bcd4;
  --color-gold: #c9a84c;
  --color-gold-light: #dfc06e;
  --color-gold-dark: #a8893d;
  --color-silver: #C0C4CC;
  --color-white: #FFFFFF;
  --color-light-bg: #F0F2F8;
  --color-text: #333333;
  --color-text-light: #666666;
  --color-text-muted: #999999;
  --font-cn: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', 'Helvetica Neue', Helvetica, Arial, sans-serif;
  --font-en: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --max-width: 1500px;
  --header-height: 80px;
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --shadow-card: 0 4px 24px rgba(13, 20, 66, 0.08);
  --shadow-card-hover: 0 12px 40px rgba(13, 20, 66, 0.15);
  --shadow-btn: 0 4px 20px rgba(0, 229, 255, 0.4);
  --transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

/* ===== Reset ===== */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: var(--font-cn);
  color: var(--color-text);
  line-height: 1.6;
  background: var(--color-white);
  overflow-x: hidden;
}
a { text-decoration: none; color: inherit; transition: var(--transition); }
img { max-width: 100%; height: auto; display: block; }
ul, ol { list-style: none; }

/* ===== Layout ===== */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 40px;
}
.section-title {
  text-align: center;
  margin-bottom: 60px;
}
.section-title h2 {
  font-size: 2.25rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 8px;
  letter-spacing: 2px;
}
.section-title .en-title {
  font-family: var(--font-en);
  font-size: 0.875rem;
  font-weight: 300;
  color: var(--color-silver);
  text-transform: uppercase;
  letter-spacing: 4px;
}
.section-title .divider {
  width: 60px;
  height: 3px;
  background: linear-gradient(90deg, var(--color-accent), var(--color-primary));
  margin: 16px auto 0;
  border-radius: 2px;
}

/* ===== Buttons ===== */
.btn-primary {
  display: inline-block;
  background: var(--color-accent);
  color: var(--color-primary-dark);
  padding: 14px 36px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 1rem;
  border: none;
  cursor: pointer;
  transition: var(--transition);
  letter-spacing: 1px;
  text-align: center;
}
.btn-primary:hover {
  background: var(--color-accent-hover);
  box-shadow: var(--shadow-btn);
  transform: translateY(-2px);
}
.btn-outline {
  display: inline-block;
  border: 2px solid var(--color-accent);
  color: var(--color-accent);
  padding: 12px 34px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 1rem;
  background: transparent;
  cursor: pointer;
  transition: var(--transition);
  letter-spacing: 1px;
  text-align: center;
}
.btn-outline:hover {
  background: rgba(0, 229, 255, 0.1);
  box-shadow: 0 4px 20px rgba(0, 229, 255, 0.2);
  transform: translateY(-2px);
}
.btn-outline-white {
  display: inline-block;
  border: 2px solid var(--color-white);
  color: var(--color-white);
  padding: 12px 34px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 1rem;
  background: transparent;
  cursor: pointer;
  transition: var(--transition);
  letter-spacing: 1px;
  text-align: center;
}
.btn-outline-white:hover {
  background: rgba(255, 255, 255, 0.1);
  transform: translateY(-2px);
}

/* ===== HEADER ===== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--header-height);
  z-index: 1000;
  transition: var(--transition);
  background: rgba(13, 20, 66, 0.95);
}
.header.scrolled {
  background: rgba(13, 20, 66, 0.97);
  box-shadow: 0 2px 20px rgba(0, 0, 0, 0.3);
  backdrop-filter: blur(10px);
}
.header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}
.logo {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}
.logo img {
  height: 50px;
  width: 50px;
  object-fit: contain;
}
.logo-text {
  display: flex;
  flex-direction: column;
  justify-content: center;
}
.logo-text .cn {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-white);
  letter-spacing: 1px;
  line-height: 1.3;
}
.logo-text .en {
  font-family: var(--font-en);
  font-size: 0.65rem;
  font-weight: 300;
  color: rgba(255, 255, 255, 0.7);
  letter-spacing: 0.5px;
  text-transform: uppercase;
}
.nav { display: flex; align-items: center; gap: 0; }
.nav a {
  color: rgba(255, 255, 255, 0.85);
  font-size: 0.95rem;
  font-weight: 400;
  padding: 0 20px;
  height: var(--header-height);
  display: flex;
  align-items: center;
  position: relative;
  letter-spacing: 1px;
}
.nav a::after {
  content: '';
  position: absolute;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%);
  width: 0;
  height: 2px;
  background: var(--color-accent);
  transition: var(--transition);
}
.nav a:hover { color: var(--color-accent); }
.nav a:hover::after, .nav a.active::after { width: 24px; }
.nav a.active { color: var(--color-accent); }
.nav-item-dropdown { position: relative; }
.nav-item-dropdown .dropdown-menu {
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%) translateY(10px);
  background: rgba(13, 20, 66, 0.97);
  backdrop-filter: blur(10px);
  border-radius: var(--radius-md);
  padding: 12px 0;
  min-width: 180px;
  opacity: 0;
  visibility: hidden;
  transition: var(--transition);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
  border: 1px solid rgba(0, 229, 255, 0.1);
}
.nav-item-dropdown:hover .dropdown-menu {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}
.dropdown-menu a {
  height: auto;
  padding: 10px 24px;
  font-size: 0.875rem;
  display: block;
  white-space: nowrap;
}
.dropdown-menu a::after { display: none; }
.dropdown-menu a:hover {
  background: rgba(0, 229, 255, 0.05);
  color: var(--color-accent);
}
.header-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}
.lang-switch {
  font-family: var(--font-en);
  font-size: 0.8rem;
  color: rgba(255, 255, 255, 0.7);
  cursor: pointer;
  padding: 6px 12px;
  border: 1px solid rgba(255, 255, 255, 0.3);
  border-radius: 4px;
  transition: var(--transition);
  letter-spacing: 1px;
  background: none;
}
.lang-switch:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 8px;
  background: none;
  border: none;
}
.hamburger span {
  width: 24px;
  height: 2px;
  background: var(--color-white);
  transition: var(--transition);
  border-radius: 1px;
}

/* ===== MOBILE NAV ===== */
.mobile-nav {
  position: fixed;
  inset: 0;
  background: rgba(13, 20, 66, 0.98);
  z-index: 999;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0;
  opacity: 0;
  visibility: hidden;
  transition: var(--transition);
}
.mobile-nav.active {
  opacity: 1;
  visibility: visible;
}
.mobile-nav a {
  color: var(--color-white);
  font-size: 1.2rem;
  padding: 16px 32px;
  letter-spacing: 2px;
  transition: var(--transition);
}
.mobile-nav a:hover { color: var(--color-accent); }
.mobile-nav-close {
  position: absolute;
  top: 20px;
  right: 24px;
  font-size: 2rem;
  color: var(--color-white);
  cursor: pointer;
  background: none;
  border: none;
  line-height: 1;
}

/* ===== FOOTER ===== */
.footer {
  background: var(--color-primary-dark);
  padding: 60px 0 0;
  color: rgba(255, 255, 255, 0.6);
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1.5fr;
  gap: 40px;
  padding-bottom: 40px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}
.footer-brand .logo { margin-bottom: 16px; }
.footer-brand p {
  font-size: 0.875rem;
  line-height: 1.8;
  color: rgba(255, 255, 255, 0.5);
}
.footer-col h5 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-white);
  margin-bottom: 20px;
  letter-spacing: 1px;
}
.footer-col ul li { margin-bottom: 10px; }
.footer-col ul li a {
  font-size: 0.875rem;
  color: rgba(255, 255, 255, 0.5);
  transition: var(--transition);
}
.footer-col ul li a:hover {
  color: var(--color-accent);
  padding-left: 4px;
}
.footer-contact-item {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  margin-bottom: 14px;
  font-size: 0.875rem;
}
.footer-contact-item .icon {
  color: var(--color-accent);
  font-size: 1rem;
  flex-shrink: 0;
  margin-top: 2px;
}
.footer-bottom {
  padding: 20px 0;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.8rem;
  color: rgba(255, 255, 255, 0.35);
}
.footer-bottom-right {
  display: flex;
  align-items: center;
  gap: 4px;
}
.footer-bottom-right a {
  color: rgba(255, 255, 255, 0.5);
  transition: var(--transition);
}
.footer-bottom-right a:hover {
  color: var(--color-accent);
}
.footer-divider {
  margin: 0 6px;
  color: rgba(255, 255, 255, 0.2);
}

/* License Modal */
.license-modal {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 9999;
  background: rgba(0,0,0,0.85);
  align-items: center;
  justify-content: center;
  cursor: zoom-out;
}
.license-modal.active { display: flex; }
.license-modal img {
  max-width: 90vw;
  max-height: 90vh;
  object-fit: contain;
  border-radius: var(--radius-md);
}
.license-modal-close {
  position: absolute;
  top: 24px;
  right: 32px;
  font-size: 2rem;
  color: #fff;
  cursor: pointer;
  z-index: 10000;
  line-height: 1;
  transition: var(--transition);
}
.license-modal-close:hover { color: var(--color-accent); }

/* ===== PAGE BANNER (sub pages) ===== */
.page-banner {
  position: relative;
  height: 360px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--color-primary-dark) 0%, var(--color-primary) 100%);
  overflow: hidden;
  margin-top: var(--header-height);
}
.page-banner::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(0,229,255,0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,229,255,0.03) 1px, transparent 1px);
  background-size: 60px 60px;
}
.page-banner-content {
  position: relative;
  z-index: 2;
  text-align: center;
}
.page-banner-content h1 {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--color-white);
  letter-spacing: 3px;
  margin-bottom: 8px;
}
.page-banner-content .en-title {
  font-family: var(--font-en);
  font-size: 1rem;
  font-weight: 300;
  color: rgba(255, 255, 255, 0.5);
  letter-spacing: 4px;
  text-transform: uppercase;
}
.page-banner .breadcrumb {
  position: absolute;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 2;
  display: flex;
  gap: 8px;
  font-size: 0.85rem;
  color: rgba(255, 255, 255, 0.5);
}
.page-banner .breadcrumb a { color: rgba(255, 255, 255, 0.5); }
.page-banner .breadcrumb a:hover { color: var(--color-accent); }
.page-banner .breadcrumb .separator { color: rgba(255, 255, 255, 0.3); }
.page-banner .breadcrumb .current { color: var(--color-accent); }

/* ===== SUB NAV (for about pages) ===== */
.sub-nav {
  background: var(--color-light-bg);
  border-bottom: 1px solid rgba(192, 196, 204, 0.3);
}
.sub-nav .container {
  display: flex;
  gap: 0;
  overflow-x: auto;
}
.sub-nav a {
  padding: 16px 28px;
  font-size: 0.95rem;
  color: var(--color-text-light);
  white-space: nowrap;
  border-bottom: 3px solid transparent;
  transition: var(--transition);
  letter-spacing: 1px;
}
.sub-nav a:hover {
  color: var(--color-primary);
  border-bottom-color: var(--color-accent);
}
.sub-nav a.active {
  color: var(--color-primary);
  font-weight: 600;
  border-bottom-color: var(--color-accent);
}

/* ===== ANIMATIONS ===== */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}
.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}
.fade-in-left {
  opacity: 0;
  transform: translateX(-30px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}
.fade-in-left.visible {
  opacity: 1;
  transform: translateX(0);
}
.fade-in-right {
  opacity: 0;
  transform: translateX(30px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}
.fade-in-right.visible {
  opacity: 1;
  transform: translateX(0);
}

/* ===== PLACEHOLDER PAGE ===== */
.placeholder-page {
  padding: 120px 0;
  text-align: center;
  min-height: 60vh;
  display: flex;
  align-items: center;
  justify-content: center;
}
.placeholder-page .placeholder-content {
  max-width: 500px;
}
.placeholder-page .placeholder-icon {
  width: 80px;
  height: 80px;
  margin: 0 auto 24px;
  background: var(--color-light-bg);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-silver);
  font-size: 2rem;
}
.placeholder-page h2 {
  font-size: 1.8rem;
  color: var(--color-primary);
  margin-bottom: 16px;
}
.placeholder-page p {
  color: var(--color-text-light);
  line-height: 1.8;
  margin-bottom: 32px;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 1024px) {
  .container { padding: 0 24px; }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 768px) {
  :root { --header-height: 64px; }
  .nav { display: none; }
  .hamburger { display: flex; }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
  .footer-brand,
  .footer-col:last-child { grid-column: span 2; }
  .footer-bottom { flex-direction: column; gap: 8px; text-align: center; }
  .page-banner { height: 260px; }
  .page-banner-content h1 { font-size: 1.8rem; }
  .section-title h2 { font-size: 1.6rem; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}