:root {
  color-scheme: light;

  /* 品牌色 */
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-primary-light: #3b82f6;
  --color-accent: #06b6d4;
  --color-deep: #0a2540;
  --color-deep-2: #0f3460;
  --color-gold: #f59e0b;

  /* 表面色 */
  --color-background: #ffffff;
  --color-surface: #ffffff;
  --color-surface-alt: #f8fafc;
  --color-surface-deep: #0a2540;

  /* 文字色 */
  --color-text: #0f172a;
  --color-text-secondary: #475569;
  --color-muted-text: #94a3b8;
  --color-text-muted: #94a3b8;
  --color-text-inverse: #ffffff;
  --color-text-inverse-muted: rgba(255, 255, 255, 0.7);

  /* 边框与分割 */
  --color-border: #e2e8f0;
  --color-border-light: #f1f5f9;
  --color-border-dark: rgba(255, 255, 255, 0.1);

  /* 功能色 */
  --color-success: #10b981;
  --color-focus: #2563eb;
  --color-focus-ring: rgba(37, 99, 235, 0.25);

  /* 字体 */
  --font-body: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  --font-display: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;

  /* 字号 */
  --fs-xs: 0.75rem;
  --fs-sm: 0.875rem;
  --fs-base: 1rem;
  --fs-lg: 1.125rem;
  --fs-xl: 1.25rem;
  --fs-2xl: 1.5rem;
  --fs-3xl: 1.875rem;
  --fs-4xl: 2.25rem;
  --fs-5xl: 3rem;
  --fs-6xl: 3.75rem;

  /* 间距 */
  --space-unit: 0.25rem;
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;
  --space-32: 8rem;

  /* 圆角 */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-2xl: 24px;
  --radius-full: 9999px;

  /* 阴影 */
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(15, 23, 42, 0.08),
    0 2px 4px -2px rgba(15, 23, 42, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(15, 23, 42, 0.08),
    0 4px 6px -4px rgba(15, 23, 42, 0.06);
  --shadow-xl: 0 20px 25px -5px rgba(15, 23, 42, 0.08),
    0 8px 10px -6px rgba(15, 23, 42, 0.06);
  --shadow-glow: 0 0 60px rgba(37, 99, 235, 0.2);

  /* 内容宽度 */
  --content-width: 1200px;
  --content-padding: var(--space-6);

  /* 层级 */
  --z-header: 100;
  --z-overlay: 200;
  --z-modal: 300;

  /* 过渡 */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  background: var(--color-background);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  margin: 0;
  min-height: 100dvh;
  overflow-x: hidden;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.2;
  margin: 0;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

p {
  margin: 0;
  color: var(--color-text-secondary);
}

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--transition-fast);
}

img,
svg {
  display: block;
  max-width: 100%;
}

button,
input,
select,
textarea {
  font: inherit;
  color: inherit;
}

button {
  cursor: pointer;
  border: none;
  background: none;
  padding: 0;
}

ul,
ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}

.skip-link {
  left: var(--space-4);
  position: fixed;
  top: var(--space-4);
  transform: translateY(-200%);
  z-index: var(--z-modal);
  background: var(--color-primary);
  color: white;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-md);
  font-weight: 600;
}

.skip-link:focus {
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}

/* ========== 通用布局 ========== */
.container {
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 0 var(--content-padding);
}

.section {
  padding: var(--space-24) 0;
}

.section-alt {
  background: var(--color-surface-alt);
}

.section-deep {
  background: var(--color-surface-deep);
  color: var(--color-text-inverse);
}

.section-head {
  text-align: center;
  max-width: 720px;
  margin: 0 auto var(--space-16);
}

.section-eyebrow {
  display: inline-block;
  font-size: var(--fs-sm);
  font-weight: 600;
  color: var(--color-primary);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: var(--space-4);
}

.section-title {
  font-size: var(--fs-4xl);
  margin-bottom: var(--space-4);
}

.section-desc {
  font-size: var(--fs-lg);
  color: var(--color-text-secondary);
}

.section-deep .section-title {
  color: var(--color-text-inverse);
}

.section-deep .section-desc {
  color: var(--color-text-inverse-muted);
}

/* ========== 按钮 ========== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  font-size: var(--fs-base);
  font-weight: 600;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  white-space: nowrap;
  line-height: 1.5;
}

.btn-primary {
  background: var(--color-primary);
  color: white;
  box-shadow: var(--shadow-md);
}

.btn-primary:hover {
  background: var(--color-primary-dark);
  transform: translateY(-1px);
  box-shadow: var(--shadow-lg);
}

.btn-secondary {
  background: transparent;
  color: var(--color-text);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.btn-ghost {
  background: transparent;
  color: var(--color-text-secondary);
}

.btn-ghost:hover {
  color: var(--color-primary);
  background: rgba(37, 99, 235, 0.06);
}

.btn-light {
  background: white;
  color: var(--color-deep);
}

.btn-light:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-lg);
}

.btn-outline-light {
  background: transparent;
  color: white;
  border: 1px solid rgba(255, 255, 255, 0.3);
}

.btn-outline-light:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.5);
}

.btn-lg {
  padding: var(--space-4) var(--space-8);
  font-size: var(--fs-lg);
}

.btn-icon {
  width: 20px;
  height: 20px;
}

/* ========== 卡片 ========== */
.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-xl);
  padding: var(--space-8);
  transition: all var(--transition-base);
}

.card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-xl);
  transform: translateY(-4px);
}

.card-icon {
  width: 56px;
  height: 56px;
  border-radius: var(--radius-lg);
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-5);
}

.card-icon svg {
  width: 28px;
  height: 28px;
  color: white;
}

.card-title {
  font-size: var(--fs-xl);
  margin-bottom: var(--space-3);
}

.card-desc {
  font-size: var(--fs-base);
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* ========== 页头导航 ========== */
.site-header {
  position: relative;
  z-index: var(--z-header);
  background: rgba(255, 255, 255, 0.94);
  border-bottom: 1px solid var(--color-border-light);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-6);
  min-height: 72px;
}

.logo {
  display: inline-flex;
  align-items: center;
  flex-shrink: 0;
  text-decoration: none;
}

.logo img {
  height: 44px;
  width: auto;
  display: block;
}

.footer-brand .logo img {
  height: 40px;
}

.logo-sub {
  display: none;
  font-size: var(--fs-xs);
  color: var(--color-text-muted);
  letter-spacing: 0.08em;
}

.main-nav {
  display: none;
  align-items: center;
  gap: var(--space-2);
}

.nav-link {
  padding: var(--space-2) var(--space-4);
  font-size: var(--fs-base);
  font-weight: 500;
  color: var(--color-text-secondary);
  border-radius: var(--radius-md);
  transition: color var(--transition-fast), background var(--transition-fast);
}

.nav-link:hover {
  color: var(--color-primary);
  background: rgba(37, 99, 235, 0.06);
}

.nav-link.active {
  color: var(--color-primary);
  font-weight: 600;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.btn-sm {
  padding: var(--space-2) var(--space-4);
  font-size: var(--fs-sm);
}

.menu-toggle {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 42px;
  height: 42px;
  padding: var(--space-3);
  border-radius: var(--radius-md);
  background: var(--color-surface-alt);
  border: 1px solid var(--color-border-light);
}

.menu-toggle span {
  width: 100%;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.menu-toggle.active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.menu-toggle.active span:nth-child(2) { opacity: 0; }
.menu-toggle.active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* 移动端导航面板 */
@media (max-width: 960px) {
  .menu-toggle { display: inline-flex; }
  .header-actions .btn { display: none; }
}

@media (min-width: 961px) {
  .main-nav { display: flex; }
  .menu-toggle { display: none; }
}

.main-nav.open {
  display: flex;
  flex-direction: column;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background: #fff;
  border-bottom: 1px solid var(--color-border-light);
  box-shadow: var(--shadow-lg);
  padding: var(--space-4) var(--space-6) var(--space-6);
  gap: var(--space-2);
}

.main-nav.open .nav-link {
  padding: var(--space-3) var(--space-4);
  font-size: var(--fs-lg);
}

/* 卡片链接 */
.card-link {
  display: inline-block;
  margin-top: var(--space-5);
  color: var(--color-primary);
  font-weight: 600;
  font-size: var(--fs-base);
}

.card-link:hover {
  text-decoration: underline;
}

/* ========== 页脚 ========== */
.site-footer {
  background: var(--color-deep);
  color: var(--color-text-inverse);
  padding-top: var(--space-24);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.6fr 1fr 1fr 1.2fr;
  gap: var(--space-12);
  padding-bottom: var(--space-16);
}

@media (max-width: 960px) {
  .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 640px) {
  .footer-grid { grid-template-columns: 1fr; }
}

.footer-brand .logo {
  margin-bottom: var(--space-4);
}

.footer-desc {
  color: var(--color-text-inverse-muted);
  line-height: 1.8;
  margin-top: var(--space-4);
  max-width: 320px;
}

.footer-col h4 {
  color: #fff;
  font-size: var(--fs-sm);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: var(--space-5);
}

.footer-col a {
  display: block;
  color: var(--color-text-inverse-muted);
  padding: var(--space-2) 0;
  font-size: var(--fs-base);
}

.footer-col a:hover {
  color: #fff;
}

.footer-col p {
  color: var(--color-text-inverse-muted);
  padding: var(--space-2) 0;
  margin: 0;
}

.footer-bottom {
  border-top: 1px solid var(--color-border-dark);
  padding: var(--space-6) 0;
}

.footer-bottom .container {
  display: flex;
  justify-content: space-between;
  gap: var(--space-4);
  flex-wrap: wrap;
  color: var(--color-text-inverse-muted);
  font-size: var(--fs-sm);
}

.footer-bottom a {
  color: var(--color-text-inverse-muted);
}

.footer-bottom a:hover {
  color: #fff;
}

/* ========== 响应式 ========== */
@media (max-width: 960px) {
  :root {
    --content-padding: var(--space-5);
  }

  .section {
    padding: var(--space-16) 0;
  }

  .section-title {
    font-size: var(--fs-3xl);
  }

  .section-head {
    margin-bottom: var(--space-12);
  }
}

@media (max-width: 640px) {
  :root {
    --content-padding: var(--space-4);
  }

  .section {
    padding: var(--space-12) 0;
  }

  .section-title {
    font-size: var(--fs-2xl);
  }

  .btn-lg {
    padding: var(--space-3) var(--space-6);
    font-size: var(--fs-base);
  }

  .card {
    padding: var(--space-6);
  }
}