/* 重置基础 */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: 'SF Pro Display', 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  font-weight: 300;
  line-height: 1.8;
  color: #FFFFFF;
  background-color: #0B1D3A;
  -webkit-font-smoothing: antialiased;
}

/* CSS 变量 */
:root {
  --color-primary: #0B1D3A;
  --color-accent: #00F5FF;
  --color-secondary: #C0C0C0;
  --color-surface-light: #1A2D4A;
  --color-surface-glass: rgba(11, 29, 58, 0.7);
  --color-text-primary: #FFFFFF;
  --color-text-secondary: #B0BEC5;
  --color-border: #2A4A7F;
  --color-shadow: rgba(0, 245, 255, 0.3);
  --color-focus: #00F5FF;
  --max-width: 1200px;
  --header-brand-height: 4rem;
  --nav-height: 3rem;
  --border-thick: 3px;
  --shadow-soft: 0 8px 32px rgba(0, 0, 0, 0.3);
  --shadow-glow: 0 0 20px var(--color-shadow);
  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;
}

/* 通用容器 */
.container {
  max-width: var(--max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.5rem;
  padding-right: 1.5rem;
}

/* 跳过链接 */
.skip-link {
  position: absolute;
  top: -100px;
  left: 0;
  z-index: 9999;
  background: var(--color-accent);
  color: var(--color-primary);
  padding: 0.8rem 1.5rem;
  font-weight: 600;
  text-decoration: none;
  transition: top 0.3s ease;
}
.skip-link:focus {
  top: 0;
}

/* 头部 */
.site-header {
  position: relative;
  background: var(--color-primary);
  border-bottom: var(--border-thick) solid var(--color-border);
  box-shadow: 0 4px 20px var(--color-shadow);
  z-index: 100;
}
.header-brand {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-brand-height);
  padding-top: 0.5rem;
  padding-bottom: 0.5rem;
}
.logo {
  font-family: 'SF Pro Display', 'Inter', -apple-system, sans-serif;
  font-weight: 700;
  font-size: 1.6rem;
  letter-spacing: -0.02em;
  color: var(--color-text-primary);
  text-transform: uppercase;
}
.tagline {
  font-family: 'PingFang SC', 'Microsoft YaHei', sans-serif;
  font-weight: 300;
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  letter-spacing: 0.05em;
}
.header-nav-wrapper {
  position: relative;
}
.header-nav {
  height: var(--nav-height);
  display: flex;
  align-items: center;
}
.header-nav ul {
  list-style: none;
  display: flex;
  gap: 0.5rem;
  width: 100%;
}
.header-nav a {
  display: inline-block;
  padding: 0.6rem 1.2rem;
  font-family: 'SF Pro Display', 'Inter', -apple-system, sans-serif;
  font-weight: 500;
  font-size: 0.95rem;
  letter-spacing: 0.03em;
  color: var(--color-text-secondary);
  text-decoration: none;
  border: 2px solid transparent;
  border-radius: 2px;
  transition: background var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast);
}
.header-nav a:hover,
.header-nav a:focus-visible {
  color: var(--color-accent);
  background: rgba(0, 245, 255, 0.08);
  border-color: var(--color-accent);
  box-shadow: var(--shadow-glow);
}
.header-nav a[aria-current="page"] {
  color: var(--color-accent);
  border-bottom: 2px solid var(--color-accent);
  background: transparent;
}
.nav-toggle {
  display: none;
  position: absolute;
  right: 1.5rem;
  top: 0.8rem;
  z-index: 110;
  background: transparent;
  border: 2px solid var(--color-border);
  border-radius: 4px;
  padding: 0.4rem 0.6rem;
  cursor: pointer;
  transition: border-color var(--transition-fast);
}
.nav-toggle:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}
.nav-toggle-icon,
.nav-toggle-icon::before,
.nav-toggle-icon::after {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text-primary);
  transition: all var(--transition-normal);
  content: '';
}
.nav-toggle-icon::before,
.nav-toggle-icon::after {
  position: relative;
}
.nav-toggle-icon::before { top: -7px; }
.nav-toggle-icon::after { top: 5px; }

/* 页脚 */
.site-footer {
  background: var(--color-primary);
  border-top: var(--border-thick) solid var(--color-border);
  padding: 2.5rem 0 2rem;
  margin-top: 4rem;
}
.footer-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1.5rem;
}
.footer-brand .logo {
  font-size: 1.3rem;
}
.footer-brand .tagline {
  font-size: 0.8rem;
  margin-top: 0.2rem;
}
.footer-legal {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  font-size: 0.9rem;
}
.footer-legal a {
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: color var(--transition-fast);
}
.footer-legal a:hover,
.footer-legal a:focus-visible {
  color: var(--color-accent);
}
.sep {
  color: var(--color-border);
}
.footer-contact {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  font-size: 0.85rem;
  color: var(--color-text-secondary);
}
.footer-meta {
  width: 100%;
  text-align: center;
  margin-top: 1.5rem;
  font-size: 0.75rem;
  color: var(--color-text-secondary);
  letter-spacing: 0.02em;
}
.footer-meta .icp,
.footer-meta .ref {
  margin: 0 0.5rem;
}

/* 通用组件 */
.btn {
  display: inline-block;
  padding: 0.7rem 2rem;
  font-family: 'SF Pro Display', 'Inter', -apple-system, sans-serif;
  font-weight: 600;
  font-size: 1rem;
  letter-spacing: 0.05em;
  text-decoration: none;
  border: 2px solid var(--color-border);
  border-radius: 2px;
  background: transparent;
  color: var(--color-text-primary);
  cursor: pointer;
  transition: all var(--transition-fast);
}
.btn:hover,
.btn:focus-visible {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-glow);
}
.btn-accent {
  background: var(--color-accent);
  color: var(--color-primary);
  border-color: var(--color-accent);
}
.btn-accent:hover,
.btn-accent:focus-visible {
  background: transparent;
  color: var(--color-accent);
  box-shadow: var(--shadow-glow);
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* 滚动进度条 (JS注入) */
[data-scroll-progress] {
  position: fixed;
  top: 0;
  left: 0;
  width: 0%;
  height: 3px;
  background: var(--color-accent);
  z-index: 9998;
  pointer-events: none;
  transition: width 0.1s linear;
}

/* 响应式 - 平板及以下 */
@media (max-width: 768px) {
  .header-brand {
    flex-direction: column;
    align-items: flex-start;
    height: auto;
    padding-top: 1rem;
    padding-bottom: 0.5rem;
  }
  .tagline {
    margin-top: 0.2rem;
  }
  .header-nav-wrapper {
    overflow: hidden;
  }
  .header-nav {
    height: 0;
    overflow: hidden;
    transition: height var(--transition-normal);
  }
  .header-nav[data-open] {
    height: auto;
    padding-bottom: 1rem;
  }
  .header-nav ul {
    flex-direction: column;
    gap: 0.25rem;
  }
  .header-nav a {
    display: block;
    width: 100%;
    padding: 0.7rem 1.2rem;
    border: none;
    border-left: 3px solid transparent;
  }
  .header-nav a[aria-current="page"] {
    border-left-color: var(--color-accent);
    background: rgba(0,245,255,0.06);
  }
  .nav-toggle {
    display: block;
  }
  .footer-inner {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }
  .footer-legal, .footer-contact {
    justify-content: center;
  }
}

/* 减少动画 */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto;
  }
  html { scroll-behavior: auto; }
}

/* :focus-visible 全局补充 */
:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}