/**
 * Modern Design System for Blog SaaS Platform
 * Includes: CSS Variables, Dark Mode, Typography, Spacing, Colors
 */

/* ============================================
   CSS Variables - Design Tokens
   ============================================ */

:root {
  /* Color Palette - Light Mode */
  --color-primary-50: #eff6ff;
  --color-primary-100: #dbeafe;
  --color-primary-200: #bfdbfe;
  --color-primary-300: #93c5fd;
  --color-primary-400: #60a5fa;
  --color-primary-500: #3b82f6;
  --color-primary-600: #2563eb;
  --color-primary-700: #1d4ed8;
  --color-primary-800: #1e40af;
  --color-primary-900: #1e3a8a;

  --color-secondary-50: #f8fafc;
  --color-secondary-100: #f1f5f9;
  --color-secondary-200: #e2e8f0;
  --color-secondary-300: #cbd5e1;
  --color-secondary-400: #94a3b8;
  --color-secondary-500: #64748b;
  --color-secondary-600: #475569;
  --color-secondary-700: #334155;
  --color-secondary-800: #1e293b;
  --color-secondary-900: #0f172a;

  --color-success-50: #f0fdf4;
  --color-success-100: #dcfce7;
  --color-success-500: #22c55e;
  --color-success-600: #16a34a;
  --color-success-700: #15803d;

  --color-warning-50: #fefce8;
  --color-warning-100: #fef9c3;
  --color-warning-500: #eab308;
  --color-warning-600: #ca8a04;
  --color-warning-700: #a16207;

  --color-error-50: #fef2f2;
  --color-error-100: #fee2e2;
  --color-error-500: #ef4444;
  --color-error-600: #dc2626;
  --color-error-700: #b91c1c;

  --color-info-50: #eff6ff;
  --color-info-100: #dbeafe;
  --color-info-500: #3b82f6;
  --color-info-600: #2563eb;
  --color-info-700: #1d4ed8;

  /* Neutral Colors */
  --color-white: #ffffff;
  --color-black: #000000;
  --color-gray-50: #f9fafb;
  --color-gray-100: #f3f4f6;
  --color-gray-200: #e5e7eb;
  --color-gray-300: #d1d5db;
  --color-gray-400: #9ca3af;
  --color-gray-500: #6b7280;
  --color-gray-600: #4b5563;
  --color-gray-700: #374151;
  --color-gray-800: #1f2937;
  --color-gray-900: #111827;

  /* Semantic Colors - Light Mode */
  --bg-primary: var(--color-white);
  --bg-secondary: var(--color-gray-50);
  --bg-tertiary: var(--color-gray-100);
  --bg-elevated: var(--color-white);
  --bg-overlay: rgba(0, 0, 0, 0.5);

  --text-primary: var(--color-gray-900);
  --text-secondary: var(--color-gray-600);
  --text-tertiary: var(--color-gray-500);
  --text-inverse: var(--color-white);
  --text-link: var(--color-primary-600);
  --text-link-hover: var(--color-primary-700);

  --border-primary: var(--color-gray-200);
  --border-secondary: var(--color-gray-300);
  --border-focus: var(--color-primary-500);

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, Monaco, 'Courier New', monospace;

  --font-size-xs: 0.75rem;      /* 12px */
  --font-size-sm: 0.875rem;     /* 14px */
  --font-size-base: 1rem;       /* 16px */
  --font-size-lg: 1.125rem;     /* 18px */
  --font-size-xl: 1.25rem;      /* 20px */
  --font-size-2xl: 1.5rem;      /* 24px */
  --font-size-3xl: 1.875rem;    /* 30px */
  --font-size-4xl: 2.25rem;     /* 36px */
  --font-size-5xl: 3rem;        /* 48px */

  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;

  --line-height-tight: 1.25;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.75;

  /* Spacing */
  --space-0: 0;
  --space-1: 0.25rem;   /* 4px */
  --space-2: 0.5rem;    /* 8px */
  --space-3: 0.75rem;   /* 12px */
  --space-4: 1rem;      /* 16px */
  --space-5: 1.25rem;   /* 20px */
  --space-6: 1.5rem;    /* 24px */
  --space-8: 2rem;      /* 32px */
  --space-10: 2.5rem;   /* 40px */
  --space-12: 3rem;     /* 48px */
  --space-16: 4rem;     /* 64px */
  --space-20: 5rem;     /* 80px */
  --space-24: 6rem;     /* 96px */

  /* Border Radius */
  --radius-none: 0;
  --radius-sm: 0.25rem;   /* 4px */
  --radius-md: 0.375rem;  /* 6px */
  --radius-lg: 0.5rem;    /* 8px */
  --radius-xl: 0.75rem;   /* 12px */
  --radius-2xl: 1rem;     /* 16px */
  --radius-full: 9999px;

  /* Shadows */
  --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px -1px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
  --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
  --shadow-inner: inset 0 2px 4px 0 rgba(0, 0, 0, 0.05);

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 200ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 300ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slower: 500ms cubic-bezier(0.4, 0, 0.2, 1);

  /* 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;
  --z-toast: 1080;

  /* Component-specific */
  --sidebar-width: 16rem;
  --header-height: 4rem;
  --container-max-width: 80rem;
}

/* ============================================
   Dark Mode Variables
   ============================================ */

[data-theme="dark"] {
  /* Dark Mode Color Overrides */
  --bg-primary: var(--color-gray-900);
  --bg-secondary: var(--color-gray-800);
  --bg-tertiary: var(--color-gray-700);
  --bg-elevated: var(--color-gray-800);
  --bg-overlay: rgba(0, 0, 0, 0.7);

  --text-primary: var(--color-gray-50);
  --text-secondary: var(--color-gray-300);
  --text-tertiary: var(--color-gray-400);
  --text-inverse: var(--color-gray-900);

  --border-primary: var(--color-gray-700);
  --border-secondary: var(--color-gray-600);

  /* Adjust shadows for dark mode */
  --shadow-xs: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.4), 0 1px 2px -1px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.5), 0 2px 4px -2px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.6), 0 4px 6px -4px rgba(0, 0, 0, 0.6);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.7), 0 8px 10px -6px rgba(0, 0, 0, 0.7);
  --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.8);
}

/* ============================================
   Base Styles
   ============================================ */

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  line-height: var(--line-height-normal);
  color: var(--text-primary);
  background-color: var(--bg-secondary);
  transition: background-color var(--transition-base), color var(--transition-base);
}

/* ============================================
   Typography
   ============================================ */

h1, h2, h3, h4, h5, h6 {
  font-weight: var(--font-weight-semibold);
  line-height: var(--line-height-tight);
  color: var(--text-primary);
  margin-bottom: var(--space-4);
}

h1 { font-size: var(--font-size-4xl); }
h2 { font-size: var(--font-size-3xl); }
h3 { font-size: var(--font-size-2xl); }
h4 { font-size: var(--font-size-xl); }
h5 { font-size: var(--font-size-lg); }
h6 { font-size: var(--font-size-base); }

p {
  margin-bottom: var(--space-4);
  color: var(--text-secondary);
}

a {
  color: var(--text-link);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--text-link-hover);
}

code, pre {
  font-family: var(--font-mono);
  font-size: var(--font-size-sm);
}

/* ============================================
   Utility Classes
   ============================================ */

.container {
  width: 100%;
  max-width: var(--container-max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--space-4);
  padding-right: var(--space-4);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* Focus visible styles */
:focus-visible {
  outline: 2px solid var(--border-focus);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* Scrollbar styling */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
  background: var(--color-gray-400);
  border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-gray-500);
}

[data-theme="dark"] ::-webkit-scrollbar-track {
  background: var(--color-gray-800);
}

[data-theme="dark"] ::-webkit-scrollbar-thumb {
  background: var(--color-gray-600);
}

[data-theme="dark"] ::-webkit-scrollbar-thumb:hover {
  background: var(--color-gray-500);
}

/* ============================================
   Selection
   ============================================ */

::selection {
  background-color: var(--color-primary-100);
  color: var(--color-primary-900);
}

[data-theme="dark"] ::selection {
  background-color: var(--color-primary-800);
  color: var(--color-primary-100);
}