:root {
  --color-bg: #f5f5f5;
  --color-bg-card: #ebebeb;
  --color-bg-dark: #1a1a1a;
  --color-text-primary: #1a1a1a;
  --color-text-secondary: #666666;
  --color-text-muted: #999999;
  --color-accent: #4a4a4a;
  --color-border: #d4d4d4;
  --color-white: #ffffff;

  --font-sans: -apple-system, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --font-mono: "SF Mono", "Fira Code", "Consolas", monospace;
  --font-size-hero: clamp(2.5rem, 5vw, 4.5rem);
  --font-size-h2: clamp(1.8rem, 3vw, 3rem);
  --font-size-h3: clamp(1.2rem, 2vw, 1.5rem);
  --font-size-body: 1.05rem;
  --font-size-small: 0.875rem;

  --section-padding: clamp(2rem, 5vw, 6rem);
  --card-padding: clamp(1.5rem, 3vw, 3rem);
  --card-radius: 16px;

  --transition-fast: 0.2s ease;
  --transition-medium: 0.4s ease;
  --transition-slow: 0.8s cubic-bezier(0.16, 1, 0.3, 1);
}