/* ========================================
   AI Forever Thing Blog - Stylesheet
   ======================================== */

/* CSS Variables */
:root {
    --color-primary: #2563eb;
    --color-primary-dark: #1d4ed8;
    --color-secondary: #0f172a;
    --color-accent: #f59e0b;
    --color-bg: #ffffff;
    --color-bg-alt: #f8fafc;
    --color-text: #334155;
    --color-text-light: #64748b;
    --color-border: #e2e8f0;
    --color-success: #10b981;
    --color-error: #ef4444;

    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'SF Mono', 'Fira Code', 'Fira Mono', Consolas, monospace;

    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;

    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-full: 9999px;

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
}

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

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

body {
    font-family: var(--font-sans);
    font-size: 1rem;
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color 0.2s ease;
}

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

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

code {
    font-family: var(--font-mono);
    font-size: 0.875em;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ========================================
   Header & Navigation
   ======================================== */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-sm);
}

.site-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 64px;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--color-secondary);
}

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

.logo-icon {
    color: var(--color-primary);
    font-size: 1.5rem;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
    list-style: none;
}

.nav-links a {
    color: var(--color-text);
    font-weight: 500;
    transition: color 0.2s ease;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--color-primary);
}

.btn-primary {
    background: var(--color-primary);
    color: white !important;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    transition: background 0.2s ease;
}

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

/* ========================================
   Blog Home
   ======================================== */
.blog-home {
    min-height: calc(100vh - 200px);
}

/* Hero Section */
.blog-hero {
    background: linear-gradient(135deg, var(--color-secondary) 0%, #1e3a5f 100%);
    color: white;
    padding: var(--spacing-3xl) 0;
    text-align: center;
}

.blog-hero h1 {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: var(--spacing-md);
}

.blog-hero p {
    font-size: 1.25rem;
    opacity: 0.9;
    margin-bottom: var(--spacing-xl);
}

.search-box {
    display: flex;
    max-width: 500px;
    margin: 0 auto;
    gap: var(--spacing-sm);
}

.search-box input {
    flex: 1;
    padding: var(--spacing-md) var(--spacing-lg);
    border: none;
    border-radius: var(--radius-md);
    font-size: 1rem;
}

.search-box button {
    padding: var(--spacing-md) var(--spacing-xl);
    background: var(--color-primary);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-weight: 600;
    transition: background 0.2s ease;
}

.search-box button:hover {
    background: var(--color-primary-dark);
}

/* Categories */
.blog-categories {
    background: var(--color-bg-alt);
    padding: var(--spacing-lg) 0;
    border-bottom: 1px solid var(--color-border);
}

.category-filters {
    display: flex;
    justify-content: center;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.category-btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    border: 1px solid var(--color-border);
    background: var(--color-bg);
    border-radius: var(--radius-full);
    cursor: pointer;
    font-weight: 500;
    transition: all 0.2s ease;
}

.category-btn:hover,
.category-btn.active {
    background: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
}

/* Articles Grid */
.blog-articles {
    padding: var(--spacing-3xl) 0;
}

.articles-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--spacing-xl);
}

.article-card {
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    transition: box-shadow 0.2s ease, transform 0.2s ease;
    position: relative;
}

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

.card-tag {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-md);
    background: var(--color-bg-alt);
    color: var(--color-text-light);
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    border-radius: var(--radius-full);
    margin-bottom: var(--spacing-md);
}

.article-card h2 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    line-height: 1.4;
}

.article-card h2 a {
    color: var(--color-secondary);
}

.article-card h2 a:hover {
    color: var(--color-primary);
}

.card-excerpt {
    color: var(--color-text-light);
    font-size: 0.95rem;
    margin-bottom: var(--spacing-md);
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.card-meta {
    display: flex;
    gap: var(--spacing-lg);
    font-size: 0.875rem;
    color: var(--color-text-light);
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-2xl);
}

.page-btn {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 1px solid var(--color-border);
    background: var(--color-bg);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-weight: 500;
    transition: all 0.2s ease;
}

.page-btn:hover,
.page-btn.active {
    background: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
}

.page-ellipsis {
    color: var(--color-text-light);
}

/* CTA Section */
.blog-cta {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    color: white;
    padding: var(--spacing-3xl) 0;
    text-align: center;
}

.blog-cta h2 {
    font-size: 2rem;
    margin-bottom: var(--spacing-md);
}

.blog-cta p {
    font-size: 1.125rem;
    opacity: 0.9;
    margin-bottom: var(--spacing-xl);
}

.btn-cta-large {
    display: inline-block;
    padding: var(--spacing-lg) var(--spacing-2xl);
    background: var(--color-bg);
    color: var(--color-primary) !important;
    font-weight: 700;
    border-radius: var(--radius-lg);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.btn-cta-large:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

/* ========================================
   Article Page
   ======================================== */
.article-page {
    padding: var(--spacing-3xl) 0;
}

.article-header {
    max-width: 800px;
    margin: 0 auto var(--spacing-2xl);
    text-align: center;
}

.article-meta {
    display: flex;
    justify-content: center;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    font-size: 0.875rem;
    color: var(--color-text-light);
}

.article-category {
    padding: var(--spacing-xs) var(--spacing-md);
    background: var(--color-bg-alt);
    border-radius: var(--radius-full);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.article-title {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--color-secondary);
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
}

.article-description {
    font-size: 1.25rem;
    color: var(--color-text-light);
    margin-bottom: var(--spacing-lg);
}

.article-author {
    font-size: 0.95rem;
    color: var(--color-text);
}

.author-label {
    color: var(--color-text-light);
}

.author-name {
    font-weight: 600;
}

/* Article Content */
.article-content {
    max-width: 800px;
    margin: 0 auto;
    font-size: 1.125rem;
    line-height: 1.8;
}

.article-content h2 {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--color-secondary);
    margin: var(--spacing-2xl) 0 var(--spacing-lg);
}

.article-content h3 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--color-secondary);
    margin: var(--spacing-xl) 0 var(--spacing-md);
}

.article-content h4 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-secondary);
    margin: var(--spacing-lg) 0 var(--spacing-sm);
}

.article-content p {
    margin-bottom: var(--spacing-lg);
}

.article-content ul,
.article-content ol {
    margin: 0 0 var(--spacing-lg) var(--spacing-xl);
}

.article-content li {
    margin-bottom: var(--spacing-sm);
}

.article-content a {
    text-decoration: underline;
}

.article-content blockquote {
    border-left: 4px solid var(--color-primary);
    padding: var(--spacing-md) var(--spacing-lg);
    margin: var(--spacing-lg) 0;
    background: var(--color-bg-alt);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

.article-content pre {
    background: var(--color-secondary);
    color: #f8fafc;
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    overflow-x: auto;
    margin: var(--spacing-lg) 0;
}

.article-content pre code {
    color: inherit;
    background: none;
}

.article-content code {
    background: var(--color-bg-alt);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    color: var(--color-primary);
}

.article-content pre code {
    background: none;
    padding: 0;
    color: inherit;
}

.article-content img {
    border-radius: var(--radius-md);
    margin: var(--spacing-lg) 0;
}

.article-content table {
    width: 100%;
    border-collapse: collapse;
    margin: var(--spacing-lg) 0;
}

.article-content th,
.article-content td {
    border: 1px solid var(--color-border);
    padding: var(--spacing-md);
    text-align: left;
}

.article-content th {
    background: var(--color-bg-alt);
    font-weight: 600;
}

/* Table of Contents */
.table-of-contents {
    background: var(--color-bg-alt);
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    margin: var(--spacing-lg) 0;
}

.table-of-contents ul {
    list-style: none;
    margin: 0;
    padding: 0;
}

.table-of-contents li {
    margin-bottom: var(--spacing-sm);
}

.table-of-contents li.h3 {
    padding-left: var(--spacing-lg);
}

/* Article Footer */
.article-footer {
    max-width: 800px;
    margin: var(--spacing-2xl) auto 0;
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--color-border);
}

.article-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xl);
}

.tag {
    padding: var(--spacing-xs) var(--spacing-md);
    background: var(--color-bg-alt);
    color: var(--color-text-light);
    font-size: 0.875rem;
    border-radius: var(--radius-full);
}

/* Article CTA */
.article-cta {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    color: white;
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    text-align: center;
    margin: var(--spacing-xl) 0;
}

.article-cta h3 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-sm);
    color: white;
}

.article-cta p {
    opacity: 0.9;
    margin-bottom: var(--spacing-lg);
}

.btn-cta {
    display: inline-block;
    padding: var(--spacing-md) var(--spacing-xl);
    background: white;
    color: var(--color-primary) !important;
    font-weight: 600;
    border-radius: var(--radius-md);
    transition: transform 0.2s ease;
}

.btn-cta:hover {
    transform: translateY(-2px);
}

/* Related Posts */
.related-posts {
    margin-top: var(--spacing-xl);
}

.related-posts h3 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    color: var(--color-secondary);
}

.related-list {
    list-style: none;
    margin: 0;
    padding: 0;
}

.related-list li {
    padding: var(--spacing-sm) 0;
    border-bottom: 1px solid var(--color-border);
}

.related-list li:last-child {
    border-bottom: none;
}

/* ========================================
   Footer
   ======================================== */
.site-footer {
    background: var(--color-secondary);
    color: #94a3b8;
    padding: var(--spacing-3xl) 0 var(--spacing-xl);
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: var(--spacing-2xl);
    margin-bottom: var(--spacing-xl);
}

.footer-brand {
    margin-bottom: var(--spacing-md);
}

.footer-brand .logo-icon {
    color: white;
}

.footer-brand .logo-text {
    color: white;
    font-size: 1.25rem;
    font-weight: 700;
}

.footer-tagline {
    margin-top: var(--spacing-sm);
    font-size: 0.95rem;
}

.footer-links h4 {
    color: white;
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

.footer-links ul {
    list-style: none;
}

.footer-links li {
    margin-bottom: var(--spacing-sm);
}

.footer-links a {
    color: #94a3b8;
    transition: color 0.2s ease;
}

.footer-links a:hover {
    color: white;
}

.footer-bottom {
    padding-top: var(--spacing-xl);
    border-top: 1px solid #334155;
    text-align: center;
    font-size: 0.875rem;
}

/* ========================================
   Responsive
   ======================================== */
@media (max-width: 768px) {
    .nav-links {
        gap: var(--spacing-md);
    }

    .blog-hero h1 {
        font-size: 2rem;
    }

    .search-box {
        flex-direction: column;
    }

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

    .footer-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }

    .article-title {
        font-size: 1.75rem;
    }

    .article-content {
        font-size: 1rem;
    }
}

@media (max-width: 480px) {
    .nav-links {
        display: none;
    }

    .category-filters {
        justify-content: flex-start;
        overflow-x: auto;
    }
}