/* Reset & Base */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  font-weight: 400;
  line-height: 1.6;
  color: #e0e0e0;
  background: linear-gradient(135deg, #0a1628 0%, #1a3a6b 50%, #2b5ea7 100%);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}
/* CSS Variables */
:root {
  --color-bg: #0a1628;
  --color-bg-mid: #1a3a6b;
  --color-bg-light: #2b5ea7;
  --color-accent: #ff6b35;
  --color-accent-hover: #ff8f5e;
  --color-silver: #c0c0c0;
  --color-card-bg: rgba(255,255,255,0.1);
  --color-card-dark: rgba(0,0,0,0.4);
  --color-text: #e0e0e0;
  --color-heading: #ffffff;
  --color-data: #ff6b35;
  --font-heading: 'Helvetica Neue', Arial, sans-serif;
  --font-body: 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-mono: 'Fira Code', 'Courier New', monospace;
  --max-width: 1200px;
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 2rem;
  --spacing-xl: 4rem;
}
/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 800;
  line-height: 1.2;
  color: var(--color-heading);
}
body { font-family: var(--font-body); color: var(--color-text); }
code, pre, .mono { font-family: var(--font-mono); }
/* Links */
a { color: var(--color-accent); text-decoration: none; transition: color 0.2s ease; }
a:hover, a:focus-visible { color: var(--color-accent-hover); }
/* Focus visible */
:focus-visible { outline: 2px solid var(--color-accent); outline-offset: 2px; }
/* Skip link */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--spacing-md);
  background: var(--color-accent);
  color: #fff;
  padding: var(--spacing-sm) var(--spacing-md);
  z-index: 1000;
  font-weight: 600;
  border-radius: 0 0 4px 4px;
}
.skip-link:focus { top: 0; }
/* Container */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}
/* Header */
.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-md) var(--spacing-lg);
  background: rgba(10,22,40,0.9);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid rgba(192,192,192,0.2);
  position: sticky;
  top: 0;
  z-index: 100;
}
.brand {
  font-family: var(--font-heading);
  font-weight: 800;
  font-size: 1.5rem;
  color: var(--color-heading);
  text-transform: uppercase;
  letter-spacing: 2px;
}
.brand:hover { color: var(--color-accent); }
/* Navigation */
.nav-container {
  display: flex;
  align-items: center;
}
.nav-list {
  display: flex;
  list-style: none;
  gap: var(--spacing-lg);
}
.nav-link {
  font-family: var(--font-heading);
  font-weight: 600;
  color: var(--color-silver);
  padding: var(--spacing-sm) 0;
  border-bottom: 2px solid transparent;
  transition: color 0.2s, border-color 0.2s;
}
.nav-link:hover, .nav-link:focus-visible {
  color: var(--color-accent);
}
.nav-link[aria-current="page"] {
  color: var(--color-heading);
  border-bottom-color: var(--color-accent);
}
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--spacing-sm);
  color: var(--color-heading);
}
.nav-toggle-icon {
  display: block;
  width: 24px;
  height: 2px;
  background: currentColor;
  position: relative;
  transition: background 0.2s;
}
.nav-toggle-icon::before, .nav-toggle-icon::after {
  content: '';
  display: block;
  width: 24px;
  height: 2px;
  background: currentColor;
  position: absolute;
  left: 0;
  transition: transform 0.2s;
}
.nav-toggle-icon::before { top: -8px; }
.nav-toggle-icon::after { top: 8px; }
[data-nav-toggle] { color: var(--color-heading); }
[data-nav-toggle][aria-expanded="true"] .nav-toggle-icon { background: transparent; }
[data-nav-toggle][aria-expanded="true"] .nav-toggle-icon::before { transform: translateY(8px) rotate(45deg); }
[data-nav-toggle][aria-expanded="true"] .nav-toggle-icon::after { transform: translateY(-8px) rotate(-45deg); }
/* Mobile nav */
@media (max-width: 768px) {
  .nav-toggle { display: block; }
  .nav-container {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: rgba(10,22,40,0.98);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    padding: var(--spacing-md);
    display: none;
    flex-direction: column;
    border-bottom: 1px solid rgba(192,192,192,0.2);
  }
  .nav-container[data-open] { display: flex; }
  .nav-list {
    flex-direction: column;
    gap: var(--spacing-md);
    width: 100%;
  }
  .nav-link { display: block; padding: var(--spacing-sm) 0; }
}
/* Footer */
.site-footer {
  background: rgba(10,22,40,0.95);
  border-top: 1px solid rgba(192,192,192,0.15);
  padding: var(--spacing-xl) 0 0;
  margin-top: var(--spacing-xl);
}
.footer-grid {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-xl);
  justify-content: space-between;
}
.footer-brand .brand { font-size: 1.3rem; }
.footer-tagline {
  margin-top: var(--spacing-sm);
  font-size: 0.85rem;
  color: var(--color-silver);
}
.footer-heading {
  font-family: var(--font-heading);
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: var(--spacing-sm);
  font-size: 1rem;
}
.footer-links ul { list-style: none; }
.footer-links li { margin-bottom: var(--spacing-sm); }
.footer-links a { color: var(--color-silver); }
.footer-links a:hover { color: var(--color-accent); }
.footer-contact dl { display: grid; grid-template-columns: auto 1fr; gap: var(--spacing-sm) var(--spacing-md); }
.footer-contact dt { font-weight: 600; color: var(--color-silver); }
.footer-contact dd { color: var(--color-text); }
.footer-contact a { color: var(--color-accent); }
.contact-note {
  margin-top: var(--spacing-sm);
  font-size: 0.8rem;
  color: dimgray;
  font-style: italic;
}
.footer-bottom {
  border-top: 1px solid rgba(192,192,192,0.1);
  padding: var(--spacing-md) 0;
  margin-top: var(--spacing-xl);
  text-align: center;
}
.footer-icp { font-size: 0.85rem; color: var(--color-silver); }
/* Buttons */
.btn {
  display: inline-block;
  padding: 0.6em 1.8em;
  font-family: var(--font-heading);
  font-weight: 700;
  color: #fff;
  background: var(--color-accent);
  border: none;
  border-radius: 4px;
  cursor: pointer;
  transition: background 0.2s, transform 0.1s;
  text-align: center;
}
.btn:hover, .btn:focus-visible {
  background: var(--color-accent-hover);
  transform: translateY(-1px);
}
.btn-secondary {
  background: transparent;
  border: 2px solid var(--color-accent);
  color: var(--color-accent);
}
.btn-secondary:hover { background: var(--color-accent); color: #fff; }
/* Card */
.card {
  background: var(--color-card-bg);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  border: 1px solid rgba(192,192,192,0.3);
  border-radius: 8px;
  padding: var(--spacing-lg);
  transition: transform 0.3s ease, box-shadow 0.3s;
}
.card:hover { transform: translateY(-4px); box-shadow: 0 8px 24px rgba(0,0,0,0.4); }
.card-dark {
  background: var(--color-card-dark);
  border-color: rgba(192,192,192,0.2);
}
/* Image wrapper */
.image-wrapper {
  position: relative;
  overflow: hidden;
  border-radius: 8px;
  background: var(--color-card-bg);
  width: 100%;
  aspect-ratio: 16 / 9;
}
.image-wrapper img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
/* Reveal animation */
.reveal { opacity: 0; transform: translateY(20px); transition: opacity 0.6s ease, transform 0.6s ease; }
.reveal.revealed { opacity: 1; transform: translateY(0); }
.reveal[data-reveal="fade"] { transform: none; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
}
/* Progress bar */
.progress-bar {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  background: var(--color-accent);
  z-index: 999;
  width: 0%;
  transition: width 0.1s linear;
  pointer-events: none;
}
/* Section title */
.section-title {
  font-size: 2rem;
  margin-bottom: var(--spacing-lg);
  border-left: 4px solid var(--color-accent);
  padding-left: var(--spacing-md);
}
/* Breadcrumb (basic) */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  list-style: none;
  gap: var(--spacing-sm);
  padding: var(--spacing-md) 0;
}
.breadcrumb li + li::before { content: '/'; margin-right: var(--spacing-sm); color: var(--color-silver); }
.breadcrumb a { color: var(--color-silver); }
.breadcrumb [aria-current="page"] { color: var(--color-heading); }
/* Responsive */
@media (max-width: 768px) {
  .footer-grid { flex-direction: column; gap: var(--spacing-lg); }
  .section-title { font-size: 1.5rem; }
}
@media (min-width: 769px) and (max-width: 1200px) {
  .container { padding: 0 var(--spacing-lg); }
}
/* Utility */
.mt-1 { margin-top: var(--spacing-md); }
.mt-2 { margin-top: var(--spacing-lg); }
.mt-3 { margin-top: var(--spacing-xl); }
.text-center { text-align: center; }
.text-accent { color: var(--color-accent); }