/* ==========================================================================
   【风格 05 · 数境青瞳】老猫云 LaoMaoYun (OLD CAT CLOUD)
   机房科技风 · 深青黑 #071512 · 荧光青 #3DF0C2 · 冷白 #E7FFF6
   无任何外部字体依赖 · 纯系统高性能字体栈 · WCAG AA 对比度合规
   ========================================================================== */

:root {
  --bg-dark: #071512;
  --bg-panel: #0a1f1a;
  --bg-panel-hover: #0f2c25;
  --bg-glass: rgba(10, 31, 26, 0.78);
  
  --cyan-core: #3DF0C2;
  --cyan-glow: rgba(61, 240, 194, 0.28);
  --cyan-subtle: rgba(61, 240, 194, 0.12);
  --cyan-border: rgba(61, 240, 194, 0.22);
  --cyan-border-active: rgba(61, 240, 194, 0.55);
  
  --text-main: #E7FFF6;
  --text-muted: #8caea4;
  --text-dark: #72a99c; /* 优化对比度 > 4.8:1，符合 WCAG AA 4.5:1 要求 */
  
  --font-title: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-num: "Space Grotesk", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
  
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 14px;
  --container-max: 1200px;
  --transition: all 0.25s cubic-bezier(0.2, 0.8, 0.2, 1);
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  background-color: var(--bg-dark);
  color: var(--text-main);
  font-family: var(--font-title);
  -webkit-font-smoothing: antialiased;
}

body {
  line-height: 1.6;
  background-color: var(--bg-dark);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
  background-image: 
    linear-gradient(rgba(61, 240, 194, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(61, 240, 194, 0.04) 1px, transparent 1px);
  background-size: 64px 64px;
  background-attachment: fixed;
  overflow-wrap: break-word;
  word-break: break-word;
}

a {
  color: inherit;
  text-decoration: none;
}

/* 键盘焦点指示器 */
:focus-visible {
  outline: 2px solid var(--cyan-core);
  outline-offset: 3px;
}

/* 键盘无障碍跳过导航入口 */
.skip-to-content {
  position: absolute;
  top: -100px;
  left: 20px;
  background: var(--cyan-core);
  color: #071512;
  padding: 10px 18px;
  font-weight: 800;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  z-index: 9999;
  border-radius: var(--radius-sm);
  transition: top 0.2s ease;
  text-decoration: none;
  box-shadow: 0 0 15px var(--cyan-glow);
}
.skip-to-content:focus {
  top: 15px;
  outline: 2px solid #ffffff;
}

/* 锚点防页眉遮挡偏移 */
.section, .article-card, [id] {
  scroll-margin-top: 86px;
}

.container {
  width: 100%;
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

/* 顶部导航栏 */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  background-color: rgba(7, 21, 18, 0.88);
  border-bottom: 1px solid var(--cyan-border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 74px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.25rem;
  font-weight: 900;
  color: var(--text-main);
}

.brand-icon {
  width: 38px;
  height: 38px;
  border-radius: var(--radius-sm);
  background: #0d2721;
  border: 1px solid var(--cyan-core);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 0 14px var(--cyan-glow);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 24px;
}

.nav-link {
  font-size: 0.92rem;
  color: var(--text-muted);
  font-weight: 500;
  transition: var(--transition);
  position: relative;
  padding: 6px 0;
}

.nav-link:hover {
  color: var(--cyan-core);
}

.nav-link::before {
  content: '[';
  opacity: 0;
  color: var(--cyan-core);
  margin-right: 2px;
  font-family: var(--font-mono);
  transition: var(--transition);
}
.nav-link::after {
  content: ']';
  opacity: 0;
  color: var(--cyan-core);
  margin-left: 2px;
  font-family: var(--font-mono);
  transition: var(--transition);
}
.nav-link:hover::before, .nav-link:hover::after {
  opacity: 1;
}

/* 按钮通用规范 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 28px;
  font-size: 0.98rem;
  font-weight: 700;
  border-radius: var(--radius-sm);
  transition: var(--transition);
  cursor: pointer;
  border: 1px solid transparent;
  text-align: center;
  white-space: nowrap;
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
}

.btn-primary {
  background: var(--cyan-core);
  color: #071512;
  box-shadow: 0 0 20px var(--cyan-glow);
  border-color: var(--cyan-core);
}

.btn-primary:hover {
  background: #5effd4;
  box-shadow: 0 0 28px rgba(61, 240, 194, 0.55);
  transform: translateY(-2px);
}

.btn-outline {
  background: rgba(61, 240, 194, 0.04);
  color: var(--text-main);
  border-color: var(--cyan-border);
}

.btn-outline:hover {
  background: rgba(61, 240, 194, 0.1);
  border-color: var(--cyan-core);
  color: var(--cyan-core);
  transform: translateY(-2px);
}

.btn-sm {
  padding: 8px 18px;
  font-size: 0.86rem;
  min-height: 38px;
}

.btn-lg {
  padding: 16px 36px;
  font-size: 1.05rem;
  min-height: 52px;
}

/* 页脚 Footer - 规范要求：只保留四个标题，在新页面打开展示 */
.footer {
  border-top: 1px solid var(--cyan-border);
  background-color: #040d0b;
  padding: 38px 0;
  margin-top: auto;
}

.footer-nav {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 36px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.footer-link {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-main);
  transition: var(--transition);
  position: relative;
  padding: 6px 4px;
}

.footer-link:hover {
  color: var(--cyan-core);
}

.footer-link::before {
  content: '[';
  color: var(--cyan-core);
  margin-right: 3px;
  opacity: 0.6;
}
.footer-link::after {
  content: ']';
  color: var(--cyan-core);
  margin-left: 3px;
  opacity: 0.6;
}

.footer-copyright {
  text-align: center;
  font-size: 0.82rem;
  color: var(--text-dark);
  font-family: var(--font-mono);
}

/* 单独子页面通用布局 */
.subpage-container {
  max-width: 880px;
  margin: 40px auto 80px;
  padding: 40px 36px;
  background: var(--bg-panel);
  border: 1px solid var(--cyan-border);
  border-radius: var(--radius-sm);
  box-shadow: 0 10px 30px rgba(0,0,0,0.4);
}

.subpage-title {
  font-size: 2.3rem;
  font-weight: 900;
  color: #ffffff;
  margin-bottom: 16px;
  border-bottom: 1px solid var(--cyan-border);
  padding-bottom: 18px;
  font-family: var(--font-title);
}

.subpage-meta {
  font-size: 0.85rem;
  color: var(--cyan-core);
  margin-bottom: 30px;
  font-family: var(--font-mono);
}

.subpage-content {
  color: var(--text-main);
  line-height: 1.8;
  font-size: 1rem;
}

.subpage-content h2 {
  font-size: 1.45rem;
  font-weight: 700;
  color: var(--cyan-core);
  margin: 36px 0 16px;
  font-family: var(--font-title);
}

.subpage-content h3 {
  font-size: 1.2rem;
  font-weight: 600;
  color: #ffffff;
  margin: 24px 0 12px;
}

.subpage-content p {
  margin-bottom: 18px;
  color: #cbe6dd;
}

.subpage-content ul, .subpage-content ol {
  margin-left: 24px;
  margin-bottom: 20px;
  color: #cbe6dd;
}

.subpage-content li {
  margin-bottom: 8px;
}

.subpage-card-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin: 24px 0 32px;
}

.subpage-card {
  background: rgba(61, 240, 194, 0.04);
  border: 1px solid var(--cyan-border);
  border-radius: var(--radius-sm);
  padding: 22px;
}

.subpage-card h4 {
  color: var(--cyan-core);
  font-size: 1.05rem;
  margin-bottom: 8px;
  font-family: var(--font-title);
}

.back-home-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 24px;
  color: var(--cyan-core);
  font-size: 0.95rem;
  font-weight: 700;
  font-family: var(--font-mono);
}

.back-home-btn:hover {
  text-decoration: underline;
}

/* 动效减弱模式 prefers-reduced-motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  #matrix-canvas {
    display: none !important;
  }
}

/* 移动端响应式 */
@media (max-width: 768px) {
  .subpage-container {
    padding: 24px 20px;
  }
  .subpage-card-grid {
    grid-template-columns: 1fr;
  }
  .subpage-title {
    font-size: 1.75rem;
  }
  .footer-nav {
    flex-direction: column;
    gap: 14px;
  }
  .btn-sm {
    min-height: 44px; /* 移动端触控热区保证 44px */
    padding: 10px 18px;
  }
}