/* ============================================
   DESIGN SYSTEM - CSS CUSTOM PROPERTIES
   ============================================ */
:root {
    /* Colors - WCAG 2.1 AA Compliant */
    --primary-bg: #2c3e50;
    --primary-text: #ffffff;
    --accent-color: #3498db;
    --accent-hover: #2980b9;
    --secondary-bg: #34495e;
    --surface-bg: #f8f9fa;
    --error-color: #e74c3c;
    --success-color: #27ae60;
    --warning-color: #f39c12;

    /* Text Colors */
    --text-primary: #2c3e50;
    --text-secondary: #666666;
    --text-muted: #888888;

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

    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 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 */

    /* Layout */
    --container-max-width: 1200px;
    --header-height: 80px;
    --border-radius: 8px;
    --border-radius-sm: 4px;

    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);

    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* ============================================
   RESET AND BASE STYLES
   ============================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: #fff;
    font-size: var(--font-size-base);
}

/* ============================================
   ACCESSIBILITY IMPROVEMENTS
   ============================================ */
/* Skip to content link for screen readers */
.skip-link {
    position: absolute;
    top: -40px;
    left: 6px;
    background: var(--primary-bg);
    color: var(--primary-text);
    padding: var(--space-sm) var(--space-md);
    text-decoration: none;
    z-index: 1000;
    border-radius: var(--border-radius-sm);
    font-weight: 600;
    transition: var(--transition-fast);
}

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

/* Focus styles for better accessibility */
a:focus,
button:focus,
input:focus,
textarea:focus,
select:focus {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

/* ============================================
   HEADER STYLES - ENHANCED
   ============================================ */
header {
    background-color: var(--primary-bg);
    color: var(--primary-text);
    height: var(--header-height);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-md);
    display: flex;
    align-items: center;
}

/* Navigation Container */
nav {
    max-width: var(--container-max-width);
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 var(--space-md);
    height: 100%;
    width: 100%;
}

/* Brand/Logo Section */
.nav-brand {
    display: flex;
    align-items: center;
    flex-shrink: 0;
    justify-content: flex-start;
}

.nav-brand .logo {
    height: 40px;
    width: auto;
    transition: var(--transition-base);
}

.nav-brand a {
    color: var(--primary-text);
    text-decoration: none;
    transition: var(--transition-base);
}

.nav-brand a:hover {
    opacity: 0.9;
}

.nav-brand a:hover .logo {
    opacity: 0.9;
}

/* Navigation Links */
.nav-links {
    display: flex;
    list-style: none;
    gap: var(--space-lg);
    align-items: center;
    margin: 0;
    padding: 0;
}

.nav-links li {
    margin: 0;
}

.nav-links a {
    color: var(--primary-text);
    text-decoration: none;
    font-weight: 500;
    font-size: var(--font-size-base);
    padding: var(--space-sm) var(--space-md);
    border-radius: var(--border-radius-sm);
    transition: var(--transition-base);
    position: relative;
}

.nav-links a:hover,
.nav-links a:focus {
    color: var(--primary-text);
    background-color: rgba(255, 255, 255, 0.1);
    transform: translateY(-1px);
}

/* Mobile Menu Toggle */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--primary-text);
    font-size: var(--font-size-2xl);
    cursor: pointer;
    padding: var(--space-sm);
    border-radius: var(--border-radius-sm);
    transition: var(--transition-base);
}

.nav-toggle:hover,
.nav-toggle:focus {
    background-color: rgba(255, 255, 255, 0.1);
}

/* Mobile Menu Styles */
@media (max-width: 768px) {
    header nav {
        justify-content: flex-start !important;
        align-items: center !important;
        display: flex !important;
        flex-direction: row !important;
    }

    header .nav-toggle {
        display: block !important;
        order: 1 !important;
        margin-right: var(--space-sm) !important;
        flex-shrink: 0 !important;
        margin-left: 0 !important;
        align-self: center !important;
    }

    header .nav-brand {
        order: 2 !important;
        flex: none !important;
        text-align: left !important;
        margin-left: 0 !important;
        margin-right: auto !important;
        align-self: center !important;
    }

    /* Force left alignment for all navigation elements */
    header nav > * {
        margin-left: 0 !important;
    }
    
    header nav > *:first-child {
        margin-right: var(--space-sm) !important;
    }

    .nav-links {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background-color: var(--primary-bg);
        flex-direction: column;
        gap: 0;
        padding: var(--space-md) 0;
        box-shadow: var(--shadow-lg);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: var(--transition-base);
        z-index: -1;
    }

    .nav-links.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-links li {
        width: 100%;
        text-align: center;
    }

    .nav-links a {
        display: block;
        padding: var(--space-md);
        border-radius: 0;
        border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    }

    .nav-links a:hover,
    .nav-links a:focus {
        background-color: rgba(255, 255, 255, 0.1);
        transform: none;
    }
}

/* ============================================
   MAIN CONTENT STYLES
   ============================================ */
main {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: var(--space-2xl) var(--space-md);
}

/* Hero Section */
.hero {
    text-align: center;
    padding: var(--space-3xl) 0;
    background: linear-gradient(135deg, var(--surface-bg) 0%, #fff 100%);
    margin-bottom: var(--space-2xl);
}

.hero h1 {
    font-size: var(--font-size-5xl);
    margin-bottom: var(--space-lg);
    color: var(--text-primary);
    font-weight: 700;
    letter-spacing: -0.025em;
    line-height: 1.2;
}

.hero p {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    margin-bottom: var(--space-lg);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
    line-height: 1.7;
}

.hero-subtitle {
    font-size: var(--font-size-base);
    color: var(--text-muted);
    margin-bottom: var(--space-2xl);
    font-style: italic;
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}

/* ============================================
   SECTION STYLES
   ============================================ */

/* Featured Posts Section */
.featured-posts {
    padding: var(--space-3xl) 0;
    background-color: var(--surface-bg);
}

.featured-posts h2 {
    text-align: center;
    margin-bottom: var(--space-2xl);
    color: var(--text-primary);
    font-size: var(--font-size-4xl);
    font-weight: 700;
}

.posts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-xl);
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--space-xl);
}

/* Post Cards - Reusable Component */
.post-card {
    background: #fff;
    padding: var(--space-xl);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    transition: var(--transition-base);
    border-left: 4px solid var(--accent-color);
    position: relative;
    overflow: hidden;
}

.post-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--accent-color), var(--accent-hover));
    transform: scaleX(0);
    transition: var(--transition-base);
}

.post-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.post-card:hover::before {
    transform: scaleX(1);
}

.post-card h3 {
    color: var(--text-primary);
    margin-bottom: var(--space-md);
    font-size: var(--font-size-lg);
    line-height: 1.4;
    font-weight: 600;
}

.post-card h3 a {
    color: var(--text-primary);
    text-decoration: none;
    transition: var(--transition-base);
}

.post-card h3 a:hover {
    color: var(--accent-color);
}

.post-card .post-meta {
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    margin-bottom: var(--space-md);
    font-weight: 500;
}

.post-card p {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: var(--space-lg);
}

.read-more {
    color: var(--accent-color);
    text-decoration: none;
    font-weight: 600;
    font-size: var(--font-size-sm);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    transition: var(--transition-base);
    border-bottom: 2px solid transparent;
}

.read-more:hover {
    color: var(--accent-hover);
    border-bottom-color: var(--accent-hover);
}

/* Categories Section */
.categories {
    padding: var(--space-3xl) 0;
    background-color: #fff;
}

.categories h2 {
    text-align: center;
    margin-bottom: var(--space-2xl);
    color: var(--text-primary);
    font-size: var(--font-size-4xl);
    font-weight: 700;
}

.categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--space-xl);
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 var(--space-xl);
}

/* Category Cards - Reusable Component */
.category-card {
    background: var(--surface-bg);
    padding: var(--space-xl);
    border-radius: var(--border-radius);
    text-align: center;
    transition: var(--transition-base);
    border: 2px solid transparent;
    position: relative;
    overflow: hidden;
}

.category-card::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    border: 2px solid var(--accent-color);
    border-radius: var(--border-radius);
    opacity: 0;
    transition: var(--transition-base);
}

.category-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.category-card:hover::after {
    opacity: 1;
    transform: scale(1.05);
}

.category-card h3 {
    color: var(--text-primary);
    margin-bottom: var(--space-md);
    font-size: var(--font-size-xl);
    font-weight: 600;
}

.category-card p {
    color: var(--text-secondary);
    line-height: 1.7;
}

/* About Section */
.about {
    padding: var(--space-3xl) var(--space-xl);
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}

.about h2 {
    color: var(--text-primary);
    margin-bottom: var(--space-xl);
    font-size: var(--font-size-4xl);
    font-weight: 700;
}

.about p {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: var(--space-lg);
}

/* CTA Button - Reusable Component */
.cta-button {
    display: inline-block;
    background-color: var(--accent-color);
    color: var(--primary-text);
    padding: var(--space-md) var(--space-xl);
    text-decoration: none;
    border-radius: var(--border-radius-sm);
    font-weight: 600;
    font-size: var(--font-size-base);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    transition: var(--transition-base);
    border: 2px solid var(--accent-color);
    position: relative;
    overflow: hidden;
}

.cta-button::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: var(--transition-base);
}

.cta-button:hover {
    background-color: var(--accent-hover);
    border-color: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.cta-button:hover::before {
    left: 100%;
}

/* SEO and Accessibility Improvements */

/* Skip to content link for accessibility */
.skip-link {
    position: absolute;
    top: -40px;
    left: 6px;
    background: #2c3e50;
    color: white;
    padding: 8px;
    text-decoration: none;
    z-index: 1000;
}

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

/* Focus styles for accessibility */
a:focus,
button:focus {
    outline: 2px solid #3498db;
    outline-offset: 2px;
}

/* Responsive design */
@media (max-width: 768px) {
    nav {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav-links {
        gap: 1rem;
    }
    
    .hero h1 {
        font-size: 2rem;
    }
    
    .hero p {
        font-size: 1.1rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .featured-posts h2,
    .categories h2,
    .about h2 {
        font-size: 2rem;
    }
    
    .posts-grid,
    .categories-grid {
        grid-template-columns: 1fr;
        padding: 0 1rem;
    }
    
    main {
        padding: 1rem;
    }
    
    .about {
        padding-left: 1rem;
        padding-right: 1rem;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 1.8rem;
    }
    
    .hero p {
        font-size: 1rem;
    }
    
    .hero-subtitle {
        font-size: 0.9rem;
    }
    
    .featured-posts h2,
    .categories h2,
    .about h2 {
        font-size: 1.8rem;
    }
    
    .post-card,
    .category-card {
        padding: var(--space-lg);
    }
}

/* ============================================
   FOOTER STYLES
   ============================================ */
footer {
    background-color: var(--secondary-bg);
    color: var(--primary-text);
    text-align: center;
    padding: var(--space-2xl) var(--space-md);
    margin-top: var(--space-3xl);
}

/* ============================================
   ADDITIONAL RESPONSIVE STYLES
   ============================================ */

/* Large Desktop Styles */
@media (min-width: 1200px) {
    :root {
        --container-max-width: 1400px;
        --header-height: 90px;
    }

    main {
        padding: var(--space-3xl) var(--space-xl);
    }

    .hero h1 {
        font-size: 3.5rem;
    }

    .posts-grid,
    .categories-grid {
        gap: var(--space-2xl);
    }
}

/* ============================================
   ACCESSIBILITY ENHANCEMENTS
   ============================================ */

/* High Contrast Mode Support */
@media (prefers-contrast: high) {
    :root {
        --primary-bg: #000000;
        --text-primary: #ffffff;
        --accent-color: #0000ff;
        --accent-hover: #0000aa;
        --surface-bg: #f0f0f0;
    }
}

/* 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;
    }

    .post-card::before,
    .category-card::after,
    .cta-button::before {
        display: none !important;
    }
}

/* ============================================
   PRINT STYLES
   ============================================ */
@media print {
    * {
        background: transparent !important;
        color: black !important;
        box-shadow: none !important;
    }

    header,
    footer,
    .nav-toggle,
    .cta-button {
        display: none !important;
    }

    .post-card,
    .category-card {
        break-inside: avoid;
        border: 1px solid #ccc;
        margin-bottom: var(--space-md);
    }

    h1, h2, h3 {
        page-break-after: avoid;
    }
}

/* ============================================
   PERFORMANCE OPTIMIZATIONS
   ============================================ */
/* Optimize font rendering */
body {
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    text-rendering: optimizeLegibility;
}

/* GPU acceleration for animations */
.post-card,
.category-card,
.cta-button,
.nav-links a {
    will-change: transform;
}

.post-card:hover,
.category-card:hover,
.cta-button:hover {
    will-change: auto;
}

/* ============================================
   UTILITY COMPONENTS
   ============================================ */

/* Scroll to Top Button */
.scroll-to-top {
    position: fixed;
    bottom: var(--space-xl);
    right: var(--space-xl);
    background-color: var(--accent-color);
    color: var(--primary-text);
    width: 50px;
    height: 50px;
    border-radius: 50%;
    border: none;
    cursor: pointer;
    display: none;
    z-index: 1000;
    box-shadow: var(--shadow-lg);
    transition: var(--transition-base);
    opacity: 0;
    transform: translateY(20px);
}

.scroll-to-top.visible {
    opacity: 1;
    transform: translateY(0);
}

.scroll-to-top:hover {
    background-color: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.scroll-to-top::before {
    content: '↑';
    font-size: var(--font-size-xl);
    font-weight: bold;
}

/* Notification Component */
.notification {
    position: fixed;
    top: calc(var(--header-height) + var(--space-md));
    right: var(--space-md);
    background-color: var(--accent-color);
    color: var(--primary-text);
    padding: var(--space-md) var(--space-lg);
    border-radius: var(--border-radius-sm);
    box-shadow: var(--shadow-md);
    z-index: 1001;
    opacity: 0;
    transform: translateX(100%);
    transition: var(--transition-base);
    max-width: 300px;
    word-wrap: break-word;
}

.notification.show {
    opacity: 1;
    transform: translateX(0);
}

.notification-error {
    background-color: var(--error-color);
}

.notification-success {
    background-color: var(--success-color);
}

.notification-warning {
    background-color: var(--warning-color);
}

/* ============================================
   MOBILE UTILITY STYLES
   ============================================ */
@media (max-width: 768px) {
    .scroll-to-top {
        bottom: var(--space-lg);
        right: var(--space-lg);
        width: 45px;
        height: 45px;
    }

    .notification {
        top: calc(var(--header-height) + var(--space-sm));
        right: var(--space-sm);
        left: var(--space-sm);
        max-width: none;
        transform: translateY(-20px);
    }
}

/* Tooltip Component */
.tooltip {
    position: absolute;
    background-color: var(--text-primary);
    color: var(--primary-text);
    padding: var(--space-xs) var(--space-sm);
    border-radius: var(--border-radius-sm);
    font-size: var(--font-size-xs);
    white-space: nowrap;
    z-index: 1002;
    opacity: 0;
    transform: translateX(-50%) translateY(5px);
    transition: var(--transition-base);
    pointer-events: none;
    box-shadow: var(--shadow-md);
}

.tooltip::after {
    content: '';
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    border: 5px solid transparent;
    border-top-color: var(--text-primary);
}

.tooltip.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}