:root {
    /* Brand Colors - Modern & Minimalist Palette */
    --color-primary: #4A90E2;           /* Vibrant blue - trust, learning, sky */
    --color-primary-dark: #357ABD;      /* Darker blue for hover states */
    --color-primary-light: #7EB3F1;     /* Light blue for backgrounds */
    --color-primary-subtle: #E8F4FD;    /* Very light blue for cards */

    --color-secondary: #50C878;         /* Emerald green - growth, success */
    --color-accent: #FFB84D;            /* Warm orange - joy, energy */

    /* Neutral Colors */
    --color-white: #FFFFFF;
    --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-error: #EF4444;
    --color-warning: #F59E0B;
    --color-info: #3B82F6;

    /* Background */
    --color-background: #FFFFFF;
    --color-surface: #F9FAFB;

    /* Typography */
    --font-family-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    --font-family-heading: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

    --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 */
    --spacing-xs: 0.25rem;        /* 4px */
    --spacing-sm: 0.5rem;         /* 8px */
    --spacing-md: 1rem;           /* 16px */
    --spacing-lg: 1.5rem;         /* 24px */
    --spacing-xl: 2rem;           /* 32px */
    --spacing-2xl: 3rem;          /* 48px */
    --spacing-3xl: 4rem;          /* 64px */
    --spacing-4xl: 6rem;          /* 96px */

    /* Border Radius */
    --radius-sm: 0.25rem;         /* 4px */
    --radius-md: 0.5rem;          /* 8px */
    --radius-lg: 0.75rem;         /* 12px */
    --radius-xl: 1rem;            /* 16px */
    --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: 200ms ease-in-out;
    --transition-slow: 300ms ease-in-out;

    /* Z-index layers */
    --z-base: 0;
    --z-dropdown: 1000;
    --z-sticky: 1100;
    --z-modal: 1200;
    --z-tooltip: 1300;

    /* Container widths */
    --container-sm: 640px;
    --container-md: 768px;
    --container-lg: 1024px;
    --container-xl: 1280px;
}