/* CSS Custom Properties - Design System */
:root {
    /* Colors - Primary (Charcoal) */
    --color-white: #FFFFFF;
    --color-black: #000000;
    --color-accent: #374151;
    --color-accent-light: #4B5563;
    --color-accent-dark: #1F2937;

    /* Gray Scale */
    --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 */
    --color-success: #10B981;
    --color-success-light: #D1FAE5;
    --color-warning: #F59E0B;
    --color-warning-light: #FEF3C7;
    --color-error: #EF4444;
    --color-error-light: #FEE2E2;
    --color-info: #6B7280;
    --color-info-light: #F3F4F6;

    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-family-mono: ui-monospace, SFMono-Regular, 'SF Mono', Consolas, 'Liberation Mono', Menlo, 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-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 */
    --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 */

    /* Border Radius */
    --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-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --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-inner: inset 0 2px 4px 0 rgb(0 0 0 / 0.05);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 200ms ease;
    --transition-slow: 300ms 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;

    /* Layout */
    --sidebar-width: 260px;
    --sidebar-collapsed-width: 72px;
    --header-height: 64px;
    --container-max-width: 1280px;

    /* Breakpoints (for reference in JS) */
    --breakpoint-sm: 640px;
    --breakpoint-md: 768px;
    --breakpoint-lg: 1024px;
    --breakpoint-xl: 1280px;
}

/* Dark mode (optional, can be toggled) */
[data-theme="dark"] {
    --color-white: #111827;
    --color-black: #FFFFFF;
    --color-gray-50: #1F2937;
    --color-gray-100: #374151;
    --color-gray-200: #4B5563;
    --color-gray-300: #6B7280;
    --color-gray-400: #9CA3AF;
    --color-gray-500: #D1D5DB;
    --color-gray-600: #E5E7EB;
    --color-gray-700: #F3F4F6;
    --color-gray-800: #F9FAFB;
    --color-gray-900: #FFFFFF;
}