/*
 * StyleHub Modern Minimalist Design System
 * Phase 1: Foundation - CSS Variables and Design Tokens
 * 
 * This file establishes the core design system that will be used
 * throughout the application for consistent, modern styling.
 */

:root {
    /* ========================================
       COLOR SYSTEM - Modern Minimalist Palette
       ======================================== */
    
    /* Primary Colors - Near Black & Pure White */
    --color-primary-dark: #1a1a1a;
    --color-primary-light: #ffffff;
    
    /* Accent Color - Vibrant Blue */
    --color-accent: #0066ff;
    --color-accent-hover: #0052cc;
    --color-accent-light: #e6f0ff;
    
    /* Gray Scale - 5 Steps for Depth */
    --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-warning: #f59e0b;
    --color-error: #ef4444;
    --color-info: #3b82f6;
    
    /* Background Colors */
    --bg-primary: var(--color-primary-light);
    --bg-secondary: var(--color-gray-50);
    --bg-tertiary: var(--color-gray-100);
    --bg-dark: var(--color-primary-dark);
    
    /* Text Colors */
    --text-primary: var(--color-primary-dark);
    --text-secondary: var(--color-gray-600);
    --text-tertiary: var(--color-gray-400);
    --text-on-dark: var(--color-primary-light);
    --text-accent: var(--color-accent);
    
    /* Border Colors */
    --border-light: var(--color-gray-200);
    --border-medium: var(--color-gray-300);
    --border-dark: var(--color-gray-400);
    
    /* ========================================
       TYPOGRAPHY SYSTEM - Fluid & Responsive
       ======================================== */
    
    /* Font Families */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', sans-serif;
    --font-display: 'Outfit', 'Inter', sans-serif;
    --font-mono: 'Fira Code', 'Courier New', monospace;
    
    /* Font Sizes - Fluid Typography using clamp() */
    --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);      /* 12-14px */
    --text-sm: clamp(0.875rem, 0.825rem + 0.25vw, 1rem);       /* 14-16px */
    --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);      /* 16-18px */
    --text-lg: clamp(1.125rem, 1.05rem + 0.375vw, 1.25rem);    /* 18-20px */
    --text-xl: clamp(1.25rem, 1.15rem + 0.5vw, 1.5rem);        /* 20-24px */
    --text-2xl: clamp(1.5rem, 1.35rem + 0.75vw, 2rem);         /* 24-32px */
    --text-3xl: clamp(1.875rem, 1.6rem + 1.375vw, 2.5rem);     /* 30-40px */
    --text-4xl: clamp(2.25rem, 1.85rem + 2vw, 3rem);           /* 36-48px */
    --text-5xl: clamp(3rem, 2.4rem + 3vw, 4rem);               /* 48-64px */
    
    /* Font Weights */
    --font-light: 300;
    --font-normal: 400;
    --font-medium: 500;
    --font-semibold: 600;
    --font-bold: 700;
    --font-black: 900;
    
    /* Line Heights */
    --leading-tight: 1.2;
    --leading-snug: 1.375;
    --leading-normal: 1.5;
    --leading-relaxed: 1.625;
    --leading-loose: 2;
    
    /* Letter Spacing */
    --tracking-tighter: -0.05em;
    --tracking-tight: -0.025em;
    --tracking-normal: 0;
    --tracking-wide: 0.025em;
    --tracking-wider: 0.05em;
    --tracking-widest: 0.1em;
    
    /* ========================================
       SPACING SYSTEM - 4px Base Unit
       ======================================== */
    
    --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 */
    --space-32: 8rem;       /* 128px */
    
    /* ========================================
       ELEVATION SYSTEM - Modern Shadows
       ======================================== */
    
    /* Subtle 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);
    
    /* Prominent Shadows */
    --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);
    
    /* Colored Shadows for CTAs */
    --shadow-accent: 0 10px 30px -5px rgba(0, 102, 255, 0.3);
    --shadow-accent-lg: 0 20px 40px -10px rgba(0, 102, 255, 0.4);
    
    /* Inner Shadows */
    --shadow-inner: inset 0 2px 4px 0 rgba(0, 0, 0, 0.05);
    
    /* ========================================
       BORDER RADIUS SYSTEM
       ======================================== */
    
    --radius-none: 0;
    --radius-sm: 0.25rem;    /* 4px */
    --radius-md: 0.5rem;     /* 8px */
    --radius-lg: 0.75rem;    /* 12px */
    --radius-xl: 1rem;       /* 16px */
    --radius-2xl: 1.5rem;    /* 24px */
    --radius-full: 9999px;   /* Fully rounded */
    
    /* ========================================
       ANIMATION & TRANSITION SYSTEM
       ======================================== */
    
    /* Durations */
    --duration-fast: 150ms;
    --duration-normal: 250ms;
    --duration-slow: 350ms;
    --duration-slower: 500ms;
    
    /* Timing Functions */
    --ease-in: cubic-bezier(0.4, 0, 1, 1);
    --ease-out: cubic-bezier(0, 0, 0.2, 1);
    --ease-in-out: cubic-bezier(0.4, 0, 0.2, 1);
    --ease-smooth: cubic-bezier(0.4, 0, 0.2, 1);
    --ease-bounce: cubic-bezier(0.68, -0.55, 0.265, 1.55);
    
    /* Common Transitions */
    --transition-base: all var(--duration-normal) var(--ease-smooth);
    --transition-fast: all var(--duration-fast) var(--ease-smooth);
    --transition-slow: all var(--duration-slow) var(--ease-smooth);
    --transition-colors: color var(--duration-normal) var(--ease-smooth),
                         background-color var(--duration-normal) var(--ease-smooth),
                         border-color var(--duration-normal) var(--ease-smooth);
    --transition-transform: transform var(--duration-normal) var(--ease-smooth);
    --transition-opacity: opacity var(--duration-normal) var(--ease-smooth);
    
    /* ========================================
       Z-INDEX SCALE
       ======================================== */
    
    --z-base: 0;
    --z-dropdown: 10;
    --z-sticky: 20;
    --z-fixed: 30;
    --z-modal-backdrop: 40;
    --z-modal: 50;
    --z-popover: 60;
    --z-tooltip: 70;
    
    /* ========================================
       LAYOUT CONSTRAINTS
       ======================================== */
    
    --container-xs: 480px;
    --container-sm: 640px;
    --container-md: 768px;
    --container-lg: 1024px;
    --container-xl: 1280px;
    --container-2xl: 1536px;
    
    /* Header Height */
    --header-height: 80px;
    --header-height-mobile: 64px;
    
    /* ========================================
       BLUR EFFECTS (Glassmorphism)
       ======================================== */
    
    --blur-sm: blur(4px);
    --blur-md: blur(8px);
    --blur-lg: blur(12px);
    --blur-xl: blur(16px);
    
    /* ========================================
       RESPONSIVE BREAKPOINTS
       ======================================== */
    
    /* These are used in media queries, not as CSS variables */
    /* 
     * --breakpoint-sm: 640px;
     * --breakpoint-md: 768px;
     * --breakpoint-lg: 1024px;
     * --breakpoint-xl: 1280px;
     * --breakpoint-2xl: 1536px;
     */
}

/* ========================================
   DARK MODE SUPPORT (Optional - Not implemented yet)
   ======================================== */

@media (prefers-color-scheme: dark) {
    /* 
     * Uncomment and customize when dark mode is needed
     * 
     * :root {
     *     --bg-primary: var(--color-gray-900);
     *     --bg-secondary: var(--color-gray-800);
     *     --text-primary: var(--color-primary-light);
     *     --text-secondary: var(--color-gray-300);
     * }
     */
}

/* ========================================
   REDUCED MOTION SUPPORT
   ======================================== */

@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* ========================================
   UTILITY CLASSES - Common Patterns
   ======================================== */

/* These will be gradually integrated into components */

/* Screen Reader Only (Accessibility) */
.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 (Keyboard Navigation) */
.focus-visible:focus {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

/* Loading State */
@keyframes skeleton-loading {
    0% {
        background-position: -200% 0;
    }
    100% {
        background-position: 200% 0;
    }
}

.skeleton {
    background: linear-gradient(
        90deg,
        var(--color-gray-200) 25%,
        var(--color-gray-100) 50%,
        var(--color-gray-200) 75%
    );
    background-size: 200% 100%;
    animation: skeleton-loading 1.5s ease-in-out infinite;
    border-radius: var(--radius-md);
}

/* Backdrop Blur (Glassmorphism) */
.backdrop-blur {
    backdrop-filter: var(--blur-md);
    -webkit-backdrop-filter: var(--blur-md);
}

.backdrop-blur-sm {
    backdrop-filter: var(--blur-sm);
    -webkit-backdrop-filter: var(--blur-sm);
}

.backdrop-blur-lg {
    backdrop-filter: var(--blur-lg);
    -webkit-backdrop-filter: var(--blur-lg);
}

/* ========================================
   END OF DESIGN SYSTEM
   ======================================== */