/* ==========================================================================
   Base CSS - Variables, Reset, Typography
   ========================================================================== */

/* CSS Variables */
:root {
    /* Colors */
    --color-primary: #4F46E5;
    --color-primary-dark: #4338CA;
    --color-primary-light: #818CF8;
    --color-secondary: #10B981;
    --color-secondary-dark: #059669;
    --color-accent: #F59E0B;
    
    /* Neutrals */
    --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 */
    --color-success: #10B981;
    --color-warning: #F59E0B;
    --color-error: #EF4444;
    --color-info: #3B82F6;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --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);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 200ms ease;
    --transition-slow: 300ms ease;
    
    /* Z-index */
    --z-dropdown: 100;
    --z-sticky: 200;
    --z-modal: 300;
    --z-tooltip: 400;
}

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

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

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-gray-800);
    background-color: var(--color-gray-50);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    color: var(--color-gray-900);
}

h1 { font-size: var(--font-size-3xl); }
h2 { font-size: var(--font-size-2xl); }
h3 { font-size: var(--font-size-xl); }

p {
    margin-bottom: var(--spacing-md);
}

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

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

strong {
    font-weight: 600;
}

/* Utility Classes */
.container {
    width: 100%;
    max-width: 480px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

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

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

button:focus-visible,
input:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* Selection */
::selection {
    background-color: var(--color-primary-light);
    color: var(--color-white);
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}

::-webkit-scrollbar-track {
    background: var(--color-gray-100);
}

::-webkit-scrollbar-thumb {
    background: var(--color-gray-300);
    border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--color-gray-400);
}

/* Responsive Typography */
@media (min-width: 768px) {
    :root {
        --font-size-3xl: 2.25rem;
        --font-size-4xl: 3rem;
    }
    
    .container {
        max-width: 640px;
    }
}

@media (min-width: 1024px) {
    .container {
        max-width: 768px;
    }
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.02);
    }
}

@keyframes shimmer {
    0% {
        background-position: -200% 0;
    }
    100% {
        background-position: 200% 0;
    }
}

.fade-in {
    animation: fadeIn var(--transition-slow) ease forwards;
}

.slide-up {
    animation: slideUp var(--transition-slow) ease forwards;
}

.pulse {
    animation: pulse 2s ease-in-out infinite;
}