/* CSS Variables - Apple-inspired Design System */
:root {
    /* Colors */
    --color-primary: #007AFF;
    --color-primary-dark: #0051D5;
    --color-text: #1d1d1f;
    --color-text-secondary: #86868b;
    --color-background: #ffffff;
    --color-surface: #f5f5f7;
    --color-border: #d2d2d7;

    /* Typography */
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 2rem;
    --font-size-3xl: 3rem;

    /* Spacing */
    --space-xs: 0.5rem;
    --space-sm: 1rem;
    --space-md: 1.5rem;
    --space-lg: 2rem;
    --space-xl: 3rem;
    --space-2xl: 4rem;

    /* Layout */
    --max-width: 1200px;
    --border-radius: 12px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Reset & Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-background);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Navigation */
.nav {
    position: sticky;
    top: 0;
    z-index: 1000;
    background-color: rgba(255, 255, 255, 0.8);
    backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 1px solid var(--color-border);
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--space-sm) var(--space-lg);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--color-text);
    text-decoration: none;
    transition: var(--transition);
}

.nav-logo:hover {
    color: var(--color-primary);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--space-lg);
}

.nav-link {
    color: var(--color-text);
    text-decoration: none;
    font-size: var(--font-size-sm);
    transition: var(--transition);
    padding: var(--space-xs) 0;
    position: relative;
}

.nav-link:hover {
    color: var(--color-primary);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 2px;
    background-color: var(--color-primary);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background-color: var(--color-text);
    transition: var(--transition);
}

/* Hero Section */
.hero {
    min-height: 70vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: var(--space-2xl) var(--space-lg);
    background: linear-gradient(135deg, rgba(245, 245, 247, 0.95) 0%, rgba(255, 255, 255, 0.95) 100%),
                url('https://images.unsplash.com/photo-1506905925346-21bda4d32df4?w=1600&h=900&fit=crop') center/cover;
    position: relative;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(245, 245, 247, 0.85) 0%, rgba(255, 255, 255, 0.85) 100%);
    z-index: 1;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 800px;
}

.hero-title {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    letter-spacing: -0.02em;
    margin-bottom: var(--space-md);
    color: var(--color-text);
}

.hero-subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    margin-bottom: var(--space-xl);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: var(--space-sm) var(--space-lg);
    font-size: var(--font-size-base);
    font-weight: 500;
    text-decoration: none;
    border-radius: var(--border-radius);
    transition: var(--transition);
    cursor: pointer;
}

.btn-primary {
    background-color: var(--color-primary);
    color: white;
}

.btn-primary:hover {
    background-color: var(--color-primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(0, 122, 255, 0.2);
}

/* Sections */
.section {
    padding: var(--space-2xl) var(--space-lg);
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
}

.section-title {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    margin-bottom: var(--space-xl);
    text-align: center;
    color: var(--color-text);
}

/* Posts Grid */
.posts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-lg);
    margin-top: var(--space-xl);
}

.post-card {
    background-color: var(--color-background);
    border-radius: var(--border-radius);
    border: 1px solid var(--color-border);
    transition: var(--transition);
    cursor: pointer;
    overflow: hidden;
}

.post-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    border-color: var(--color-primary);
}

.post-card-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
    transition: var(--transition);
}

.post-card:hover .post-card-image {
    transform: scale(1.05);
}

.post-card-content {
    padding: var(--space-lg);
}

.post-date {
    display: block;
    font-size: var(--font-size-xs);
    color: var(--color-text-secondary);
    margin-bottom: var(--space-sm);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.post-title {
    font-size: var(--font-size-xl);
    font-weight: 600;
    margin-bottom: var(--space-sm);
    color: var(--color-text);
}

.post-excerpt {
    font-size: var(--font-size-base);
    color: var(--color-text-secondary);
    line-height: 1.7;
    margin-bottom: var(--space-md);
}

.post-link {
    display: inline-block;
    color: var(--color-primary);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
}

.post-link:hover {
    transform: translateX(4px);
}

/* Post Detail Page */
.post-header {
    text-align: center;
    padding: var(--space-2xl) var(--space-lg);
    background-color: var(--color-surface);
}

.post-header-title {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    margin-bottom: var(--space-md);
}

.post-header-date {
    font-size: var(--font-size-base);
    color: var(--color-text-secondary);
}

.post-featured-image {
    max-width: 1200px;
    margin: 0 auto;
    overflow: hidden;
}

.post-featured-image img {
    width: 100%;
    height: auto;
    display: block;
}

.post-content {
    max-width: 720px;
    margin: 0 auto;
    padding: var(--space-2xl) var(--space-lg);
}

.post-content p {
    margin-bottom: var(--space-md);
    line-height: 1.8;
}

.post-content h2 {
    font-size: var(--font-size-xl);
    font-weight: 600;
    margin-top: var(--space-xl);
    margin-bottom: var(--space-md);
}

.post-content img {
    max-width: 100%;
    border-radius: var(--border-radius);
    margin: var(--space-lg) 0;
}

/* About Page */
.about-section {
    max-width: 720px;
    margin: 0 auto;
    padding: var(--space-2xl) var(--space-lg);
}

.about-section h2 {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    margin-bottom: var(--space-md);
}

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

/* Footer */
.footer {
    background-color: var(--color-surface);
    padding: var(--space-xl) var(--space-lg);
    margin-top: var(--space-2xl);
}

.footer-text {
    text-align: center;
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 60px;
        left: -100%;
        flex-direction: column;
        background-color: rgba(255, 255, 255, 0.95);
        backdrop-filter: blur(20px);
        width: 100%;
        padding: var(--space-lg);
        gap: var(--space-sm);
        transition: var(--transition);
        border-bottom: 1px solid var(--color-border);
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-toggle {
        display: flex;
    }

    .hero-title {
        font-size: var(--font-size-2xl);
    }

    .hero-subtitle {
        font-size: var(--font-size-base);
    }

    .section-title {
        font-size: var(--font-size-xl);
    }

    .posts-grid {
        grid-template-columns: 1fr;
    }

    .post-header-title {
        font-size: var(--font-size-2xl);
    }
}

/* Animations */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.post-card,
.hero-content {
    animation: fadeIn 0.6s ease-out;
}

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

/* Print Styles */
@media print {
    .nav,
    .footer,
    .btn {
        display: none;
    }
}