/* ==========================================================================
   Aeranking Design System - CSS Variables
   Requirements: 8.1 (Color Palette), 8.2 (Typography), 8.3 (Spacing/Grid)
   ========================================================================== */

:root {
  /* ==========================================================================
     COLOR PALETTE (Requirement 8.1)
     ========================================================================== */
  
  /* Primary Colors - Brand Identity */
  --color-primary: #18181b;
  --color-primary-hover: #27272a;
  --color-primary-light: #3f3f46;
  --color-primary-dark: #09090b;
  
  /* Secondary Colors - Accent (using teal/green instead of purple) */
  --color-secondary: #0d9488;
  --color-secondary-hover: #0f766e;
  --color-secondary-light: #14b8a6;
  --color-secondary-dark: #115e59;
  
  /* Neutral Colors - Grays (brighter) */
  --color-gray-50: #fafafa;
  --color-gray-100: #f5f5f5;
  --color-gray-200: #e5e5e5;
  --color-gray-300: #d4d4d4;
  --color-gray-400: #a3a3a3;
  --color-gray-500: #737373;
  --color-gray-600: #525252;
  --color-gray-700: #404040;
  --color-gray-800: #262626;
  --color-gray-900: #171717;
  
  /* Semantic Colors */
  --color-success: #10b981;
  --color-success-light: #34d399;
  --color-warning: #f59e0b;
  --color-warning-light: #fbbf24;
  --color-error: #ef4444;
  --color-error-light: #f87171;
  --color-info: #3b82f6;
  --color-info-light: #60a5fa;
  
  /* Background Colors */
  --color-bg-primary: #ffffff;
  --color-bg-secondary: #fafafa;
  --color-bg-tertiary: #f5f5f5;
  --color-bg-dark: #171717;
  
  /* Text Colors */
  --color-text-primary: #171717;
  --color-text-secondary: #525252;
  --color-text-tertiary: #737373;
  --color-text-muted: #a3a3a3;
  --color-text-inverse: #ffffff;
  
  /* Border Colors */
  --color-border-light: #e5e5e5;
  --color-border-default: #d4d4d4;
  --color-border-dark: #a3a3a3;
  
  /* ==========================================================================
     TYPOGRAPHY SCALE (Requirement 8.2)
     ========================================================================== */
  
  /* Font Families */
  --font-family-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-family-mono: 'Fira Code', 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, monospace;
  
  /* Font Sizes - Using modular scale (1.25 ratio) */
  --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-size-6xl: 3.75rem;    /* 60px */
  
  /* Font Weights */
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  --font-weight-extrabold: 800;
  
  /* Line Heights */
  --line-height-tight: 1.25;
  --line-height-snug: 1.375;
  --line-height-normal: 1.5;
  --line-height-relaxed: 1.625;
  --line-height-loose: 2;
  
  /* Letter Spacing */
  --letter-spacing-tight: -0.025em;
  --letter-spacing-normal: 0;
  --letter-spacing-wide: 0.025em;
  --letter-spacing-wider: 0.05em;
  
  /* ==========================================================================
     SPACING SYSTEM (Requirement 8.3)
     ========================================================================== */
  
  /* Base spacing unit: 4px */
  --spacing-0: 0;
  --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 */
  --spacing-32: 8rem;     /* 128px */
  
  /* ==========================================================================
     LAYOUT GRID SYSTEM (Requirement 8.3)
     ========================================================================== */
  
  /* Container widths */
  --container-sm: 640px;
  --container-md: 768px;
  --container-lg: 1024px;
  --container-xl: 1280px;
  --container-2xl: 1440px;
  
  /* Grid */
  --grid-columns: 12;
  --grid-gap: var(--spacing-6);
  
  /* ==========================================================================
     BREAKPOINTS (Requirement 6.1, 6.2, 6.3)
     ========================================================================== */
  
  /* Mobile-first breakpoints (use in media queries) */
  --breakpoint-sm: 640px;   /* Small devices */
  --breakpoint-md: 768px;   /* Tablets */
  --breakpoint-lg: 1024px;  /* Desktops */
  --breakpoint-xl: 1280px;  /* Large desktops */
  --breakpoint-2xl: 1536px; /* Extra large screens */
  
  /* ==========================================================================
     EFFECTS & DECORATIONS
     ========================================================================== */
  
  /* Border Radius */
  --radius-none: 0;
  --radius-sm: 0.25rem;    /* 4px */
  --radius-default: 0.375rem; /* 6px */
  --radius-md: 0.5rem;     /* 8px */
  --radius-lg: 0.75rem;    /* 12px */
  --radius-xl: 1rem;       /* 16px */
  --radius-2xl: 1.5rem;    /* 24px */
  --radius-full: 9999px;
  
  /* Box Shadows */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-default: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
  --shadow-2xl: 0 25px 50px -12px rgb(0 0 0 / 0.25);
  --shadow-inner: inset 0 2px 4px 0 rgb(0 0 0 / 0.05);
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-default: 200ms ease;
  --transition-slow: 300ms ease;
  --transition-slower: 500ms ease;
  
  /* Z-Index Scale */
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-fixed: 300;
  --z-modal-backdrop: 400;
  --z-modal: 500;
  --z-popover: 600;
  --z-tooltip: 700;
}

/* ==========================================================================
   BASE RESET & DEFAULTS
   ========================================================================== */

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-family-sans);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-normal);
  line-height: var(--line-height-normal);
  color: var(--color-text-primary);
  background-color: var(--color-bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Typography defaults */
h1, h2, h3, h4, h5, h6 {
  font-weight: var(--font-weight-bold);
  line-height: var(--line-height-tight);
  color: var(--color-text-primary);
}

h1 { font-size: var(--font-size-5xl); }
h2 { font-size: var(--font-size-4xl); }
h3 { font-size: var(--font-size-3xl); }
h4 { font-size: var(--font-size-2xl); }
h5 { font-size: var(--font-size-xl); }
h6 { font-size: var(--font-size-lg); }

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

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

a:hover {
  color: var(--color-primary-hover);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* Focus styles for accessibility */
:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* Selection styles */
::selection {
  background-color: var(--color-primary);
  color: var(--color-text-inverse);
}