/* CSS Custom Properties (Variables) */

:root {
  /* Color Palette */
  --primary-color: #0066cc;
  --primary-hover: #0052a3;
  --secondary-color: #00cc66;
  --secondary-hover: #00a352;
  --accent-color: #ff6600;
  
  /* Text Colors */
  --text-primary: #333333;
  --text-secondary: #666666;
  --text-light: #999999;
  --text-white: #ffffff;
  
  /* Background Colors */
  --bg-primary: #ffffff;
  --bg-secondary: #f5f5f5;
  --bg-dark: #1a1a1a;
  --bg-overlay: rgba(0, 0, 0, 0.5);
  
  /* Border Colors */
  --border-color: #e0e0e0;
  --border-light: #f0f0f0;
  
  /* Spacing System (8px base unit) */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
  --spacing-2xl: 48px;
  --spacing-3xl: 64px;
  --spacing-4xl: 96px;
  
  /* Typography */
  --font-family-base: "PingFang TC", "PingFang SC", -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
  --font-family-heading: "PingFang TC", "PingFang SC", 'Microsoft YaHei', sans-serif;
  
  --font-size-xs: 12px;
  --font-size-sm: 14px;
  --font-size-base: 16px;
  --font-size-lg: 18px;
  --font-size-xl: 20px;
  --font-size-2xl: 24px;
  --font-size-3xl: 32px;
  --font-size-4xl: 40px;
  --font-size-5xl: 48px;
  
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  
  --line-height-tight: 1.2;
  --line-height-normal: 1.6;
  --line-height-relaxed: 1.8;
  
  /* Layout */
  --max-width: 1200px;
  --max-width-wide: 1400px;
  --max-width-narrow: 800px;
  
  --header-height: 70px;
  --header-height-mobile: 60px;
  
  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 9999px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.15);
  
  /* Transitions */
  --transition-fast: 0.2s ease;
  --transition-base: 0.3s ease;
  --transition-slow: 0.4s ease;
  
  /* Z-index Layers */
  --z-dropdown: 1000;
  --z-sticky: 1020;
  --z-fixed: 1030;
  --z-modal-backdrop: 1040;
  --z-modal: 1050;
  --z-popover: 1060;
  --z-tooltip: 1070;
  
  /* Breakpoints (for reference in JavaScript) */
  --breakpoint-mobile: 320px;
  --breakpoint-tablet: 768px;
  --breakpoint-desktop: 1024px;
  --breakpoint-wide: 1440px;
  --breakpoint-max: 1920px;
}

/* Dark mode support (optional for future enhancement) */
@media (prefers-color-scheme: dark) {
  :root {
    --text-primary: #e0e0e0;
    --text-secondary: #b0b0b0;
    --text-light: #808080;
    --bg-primary: #1a1a1a;
    --bg-secondary: #2a2a2a;
    --border-color: #404040;
    --border-light: #303030;
  }
}