/**
 * CSS Custom Properties (Variables)
 * Single source of truth for design tokens
 * 
 * Usage: var(--color-primary), var(--spacing-md), etc.
 */

:root {
  /* ========================================
     COLORS - Academic Design v2.0 Palette
     ======================================== */
  
  /* Primary Colors */
  --color-primary: #007bff;
  --color-primary-dark: #0056b3;
  --color-primary-light: #4da3ff;
  
  /* Secondary Colors */
  --color-secondary: #6c757d;
  --color-secondary-dark: #545b62;
  --color-secondary-light: #868e96;
  
  /* Semantic Colors */
  --color-success: #28a745;
  --color-warning: #ffc107;
  --color-danger: #dc3545;
  --color-info: #17a2b8;
  
  /* Text Colors */
  --color-text: #212529;
  --color-text-muted: #6c757d;
  --color-text-light: #adb5bd;
  
  /* Background Colors */
  --color-background: #ffffff;
  --color-background-alt: #f8f9fa;
  --color-background-code: #f5f5f5;
  
  /* Border Colors */
  --color-border: #dee2e6;
  --color-border-light: #e9ecef;
  --color-border-dark: #ced4da;
  
  /* Chart.js Default Colors */
  --color-chart-primary: rgb(52, 152, 219);
  --color-chart-secondary: rgb(155, 89, 182);
  --color-chart-accent: rgb(46, 204, 113);
  
  /* ========================================
     SPACING SCALE (8px base)
     ======================================== */
  
  --spacing-xs: 0.25rem;   /* 4px */
  --spacing-sm: 0.5rem;    /* 8px */
  --spacing-md: 1rem;      /* 16px */
  --spacing-lg: 2rem;      /* 32px */
  --spacing-xl: 3rem;      /* 48px */
  --spacing-xxl: 4rem;     /* 64px */
  
  /* Component-Specific Spacing */
  --spacing-gutter: 1.5rem;       /* Grid gutters */
  --spacing-section: 3rem;        /* Section separation */
  --spacing-component: 2rem;      /* Between major components */
  
  /* ========================================
     TYPOGRAPHY
     ======================================== */
  
  /* Font Families */
  --font-primary: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: 'Courier New', Courier, monospace;
  --font-serif: Georgia, 'Times New Roman', serif;
  
  /* Font Sizes */
  --font-size-xs: 0.75rem;    /* 12px */
  --font-size-sm: 0.875rem;   /* 14px */
  --font-size-md: 1rem;       /* 16px - base */
  --font-size-lg: 1.25rem;    /* 20px */
  --font-size-xl: 1.5rem;     /* 24px */
  --font-size-xxl: 2rem;      /* 32px */
  --font-size-xxxl: 2.5rem;   /* 40px */
  
  /* Line Heights */
  --line-height-tight: 1.2;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;
  
  /* Font Weights */
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-bold: 700;
  
  /* ========================================
     BORDER RADIUS - Academic Design v2.0
     ======================================== */
  
  --radius-none: 0;
  --radius-sm: 2px;    /* Minimal rounding (buttons, inputs) */
  --radius-md: 4px;    /* Standard components */
  --radius-lg: 8px;    /* Cards, containers */
  --radius-round: 50%; /* Circular elements */
  
  /* ========================================
     SHADOWS
     ======================================== */
  
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 2px 4px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 4px 8px rgba(0, 0, 0, 0.15);
  --shadow-xl: 0 8px 16px rgba(0, 0, 0, 0.2);
  
  /* ========================================
     TRANSITIONS & ANIMATIONS
     ======================================== */
  
  --transition-fast: 150ms ease;
  --transition-medium: 300ms ease;
  --transition-slow: 500ms ease;
  
  --easing-standard: cubic-bezier(0.4, 0.0, 0.2, 1);
  --easing-decelerate: cubic-bezier(0.0, 0.0, 0.2, 1);
  --easing-accelerate: cubic-bezier(0.4, 0.0, 1, 1);
  
  /* ========================================
     Z-INDEX SCALE
     ======================================== */
  
  --z-base: 0;
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-navigation: 300;
  --z-modal-backdrop: 400;
  --z-modal: 500;
  --z-popover: 600;
  --z-tooltip: 700;
  
  /* ========================================
     TYPOGRAPHY
     ======================================== */
  
  /* Font Families */
  --font-primary: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: 'SFMono-Regular', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, 'Courier New', monospace;
  --font-serif: Georgia, 'Times New Roman', Times, serif;
  
  /* Font Sizes */
  --font-size-xs: 0.75rem;   /* 12px */
  --font-size-sm: 0.875rem;  /* 14px */
  --font-size-md: 1rem;      /* 16px - base */
  --font-size-lg: 1.125rem;  /* 18px */
  --font-size-xl: 1.25rem;   /* 20px */
  --font-size-xxl: 1.5rem;   /* 24px */
  --font-size-3xl: 1.875rem; /* 30px */
  --font-size-4xl: 2.25rem;  /* 36px */
  
  /* Font Weights */
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  
  /* Line Heights */
  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;
  
  /* ========================================
     LAYOUT CONSTRAINTS
     ======================================== */
  
  --max-width-content: 1200px;
  --max-width-text: 800px;
  --max-width-narrow: 600px;
  
  /* ========================================
     BREAKPOINTS (for reference in media queries)
     Note: Cannot use these directly in @media, must hardcode values
     ======================================== */
  
  --breakpoint-mobile: 480px;
  --breakpoint-tablet: 768px;
  --breakpoint-desktop: 1024px;
  --breakpoint-wide: 1280px;
}

/**
 * Dark Mode Variables (Future Enhancement)
 * Uncomment and adjust when dark mode support added
 */
/*
@media (prefers-color-scheme: dark) {
  :root {
    --color-background: #1a1a1a;
    --color-background-alt: #2d2d2d;
    --color-text: #f8f9fa;
    --color-text-muted: #adb5bd;
    --color-border: #495057;
  }
}
*/