/**
 * CSS Custom Properties - Design System Variables
 * Academic Website Modernization
 */

:root {
  /* Color Palette */
  --color-primary: #1e3a8a;
  --color-secondary: #6b7280;
  --color-accent: #0d9488;
  --color-background: #fafafa;
  --color-text: #1f2937;
  --color-text-light: #6b7280;
  --color-border: #e5e7eb;
  --color-white: #ffffff;
  
  /* Link Colors */
  --color-link: #1e3a8a;
  --color-link-hover: #0d9488;
  
  /* Typography */
  --font-body: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-heading: 'Crimson Pro', Georgia, 'Times New Roman', serif;
  
  /* Font Sizes */
  --font-size-base: 1rem;
  --font-size-sm: 0.875rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  
  /* Heading Sizes */
  --font-size-h1: 2.5rem;
  --font-size-h2: 2rem;
  --font-size-h3: 1.75rem;
  --font-size-h4: 1.5rem;
  --font-size-h5: 1.25rem;
  --font-size-h6: 1rem;
  
  /* Line Heights */
  --line-height-base: 1.6;
  --line-height-heading: 1.2;
  --line-height-tight: 1.4;
  
  /* Font Weights */
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  
  /* Spacing Scale (based on 4px unit) */
  --spacing-1: 0.25rem;  /* 4px */
  --spacing-2: 0.5rem;   /* 8px */
  --spacing-3: 0.75rem;  /* 12px */
  --spacing-4: 1rem;     /* 16px */
  --spacing-5: 1.25rem;  /* 20px */
  --spacing-6: 1.5rem;   /* 24px */
  --spacing-8: 2rem;     /* 32px */
  --spacing-10: 2.5rem;  /* 40px */
  --spacing-12: 3rem;    /* 48px */
  --spacing-16: 4rem;    /* 64px */
  --spacing-20: 5rem;    /* 80px */
  --spacing-24: 6rem;    /* 96px */
  
  /* Border Radius */
  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  
  /* Transitions */
  --transition-fast: 150ms ease-in-out;
  --transition-base: 250ms ease-in-out;
  --transition-slow: 350ms ease-in-out;
  
  /* Z-index Scale */
  --z-dropdown: 1000;
  --z-sticky: 1020;
  --z-fixed: 1030;
  --z-modal-backdrop: 1040;
  --z-modal: 1050;
  --z-popover: 1060;
  --z-tooltip: 1070;
  
  /* Container Max Width */
  --container-max-width: 1140px;
  
  /* Breakpoints (for reference in media queries) */
  --breakpoint-sm: 576px;
  --breakpoint-md: 768px;
  --breakpoint-lg: 992px;
  --breakpoint-xl: 1200px;
  --breakpoint-xxl: 1400px;
}