:root {
  /* ===== Apple Clarity Theme ===== */

  /* Colors — Apple 官网精准色值 */
  --color-bg: #ffffff;
  --color-bg-alt: #f5f5f7;
  --color-bg-dark: #000000;
  --color-bg-dark-alt: #1d1d1f;

  --color-text: #1d1d1f;
  --color-text-secondary: #6e6e73;
  --color-text-muted: #86868b;
  --color-text-light: #f5f5f7;
  --color-text-light-muted: rgba(255, 255, 255, 0.56);

  --color-accent: #0071e3;
  --color-accent-hover: #0077ed;
  --color-accent-light: rgba(0, 113, 227, 0.07);

  --color-border: rgba(0, 0, 0, 0.08);
  --color-border-hover: rgba(0, 0, 0, 0.16);

  /* Cosmic palette — 品牌签名渐变（装饰用，保留星空感） */
  --cosmic-blue: #1e3a5f;
  --cosmic-violet: #4a1d6b;
  --cosmic-teal: #0d9488;
  --gradient-cosmic: linear-gradient(135deg, #3b82f6 0%, #06b6d4 100%);
  --gradient-cosmic-soft: linear-gradient(135deg, rgba(59,130,246,0.06), rgba(6,182,212,0.06));
  --gradient-dark: linear-gradient(160deg, #000000 0%, #1d1d1f 50%, #000000 100%);

  /* ===== Typography — Apple 系统字体栈 ===== */
  --font-display: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'Segoe UI', 'Helvetica Neue', sans-serif;
  --font-body: -apple-system, BlinkMacSystemFont, 'SF Pro Text', 'Segoe UI', 'Helvetica Neue', sans-serif;
  --font-cn: -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;

  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1.0625rem;
  --text-lg: 1.1875rem;
  --text-xl: 1.3125rem;
  --text-2xl: 1.5rem;
  --text-3xl: 2rem;
  --text-4xl: 2.8125rem;
  --text-5xl: 3.5rem;
  --text-hero: 5.5rem;

  /* ===== Spacing ===== */
  --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;

  /* ===== Radius — Apple 偏好更圆润 ===== */
  --radius-sm: 10px;
  --radius-md: 14px;
  --radius-lg: 18px;
  --radius-xl: 28px;
  --radius-2xl: 36px;
  --radius-full: 9999px;

  /* ===== Motion — Apple 弹性缓动 ===== */
  --ease-out: cubic-bezier(0.25, 0.46, 0.45, 0.94);
  --ease-in-out: cubic-bezier(0.42, 0, 0.58, 1);
  --dur-fast: 200ms;
  --dur-base: 300ms;
  --dur-slow: 500ms;

  /* ===== Layout ===== */
  --container-max: 980px;
  --container-wide: 1200px;
  --container-pad: 2rem;
  --nav-h: 48px;

  /* ===== Shadows — Apple 极淡阴影 ===== */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 2px 8px rgba(0, 0, 0, 0.06), 0 4px 12px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 4px 12px rgba(0, 0, 0, 0.06), 0 12px 28px rgba(0, 0, 0, 0.08);
  --shadow-xl: 0 8px 24px rgba(0, 0, 0, 0.08), 0 24px 48px rgba(0, 0, 0, 0.06);
}