/* Base Styles - Typography, Colors, Reset */

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

html {
    font-size: 16px;
    line-height: 1.6;
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* CSS Custom Properties - Brand Colors */
:root {
    /* Primary Brand Colors */
    --primary-blue: #1e3a8a;
    --primary-blue-light: #3b82f6;
    --primary-blue-dark: #1e40af;
    
    /* Secondary Colors */
    --secondary-gray: #6b7280;
    --secondary-gray-light: #9ca3af;
    --secondary-gray-dark: #374151;
    
    /* Accent Colors */
    --accent-green: #059669;
    --accent-orange: #ea580c;
    
    /* Neutral Colors */
    --white: #ffffff;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    
    /* Semantic Colors */
    --text-primary: var(--gray-900);
    --text-secondary: var(--gray-600);
    --text-muted: var(--gray-500);
    --bg-primary: var(--white);
    --bg-secondary: var(--gray-50);
    --border-color: var(--gray-200);
    
    /* Interactive Colors */
    --link-color: var(--primary-blue);
    --link-hover: var(--primary-blue-dark);
    --button-primary: var(--primary-blue);
    --button-primary-hover: var(--primary-blue-dark);
    
    /* Spacing Scale */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    
    /* Typography Scale */
    --text-xs: 0.75rem;
    --text-sm: 0.875rem;
    --text-base: 1rem;
    --text-lg: 1.125rem;
    --text-xl: 1.25rem;
    --text-2xl: 1.5rem;
    --text-3xl: 1.875rem;
    --text-4xl: 2.25rem;
    --text-5xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.375rem;
    --radius-lg: 0.5rem;
    --radius-xl: 0.75rem;
    
    /* 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);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: var(--space-md);
    color: var(--text-primary);
}

h1 {
    font-size: var(--text-4xl);
}

h2 {
    font-size: var(--text-3xl);
}

h3 {
    font-size: var(--text-2xl);
}

h4 {
    font-size: var(--text-xl);
}

h5 {
    font-size: var(--text-lg);
}

h6 {
    font-size: var(--text-base);
}

p {
    margin-bottom: var(--space-md);
    color: var(--text-primary);
}

/* Links */
a {
    color: var(--link-color);
    text-decoration: none;
    transition: color var(--transition-fast);
}

a:hover,
a:focus {
    color: var(--link-hover);
    text-decoration: underline;
}

a:focus {
    outline: 2px solid var(--primary-blue);
    outline-offset: 2px;
}

/* Lists */
ul, ol {
    margin-bottom: var(--space-md);
    padding-left: var(--space-lg);
}

li {
    margin-bottom: var(--space-xs);
    color: var(--text-primary);
}

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

/* Form Elements */
button {
    font-family: inherit;
    font-size: inherit;
    cursor: pointer;
    border: none;
    background: none;
    transition: all var(--transition-fast);
}

button:focus {
    outline: 2px solid var(--primary-blue);
    outline-offset: 2px;
}

/* 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: 0;
}

/* Focus management for skip links */
.skip-link {
    position: absolute;
    top: -40px;
    left: 6px;
    background: var(--primary-blue);
    color: var(--white);
    padding: 8px;
    text-decoration: none;
    border-radius: var(--radius-md);
    z-index: 1000;
}

.skip-link:focus {
    top: 6px;
}

/* Reduced motion preferences */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --border-color: var(--gray-900);
        --text-secondary: var(--gray-900);
    }
}

/* Dark mode support (future enhancement) */
@media (prefers-color-scheme: dark) {
    :root {
        --text-primary: var(--gray-100);
        --text-secondary: var(--gray-300);
        --text-muted: var(--gray-400);
        --bg-primary: var(--gray-900);
        --bg-secondary: var(--gray-800);
        --border-color: var(--gray-700);
    }
}