/* NotebookLM Guide - Clean & Fast CSS */
/* Design Philosophy: Speed > Beauty, Content > Style */

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

:root {
    --primary: #2563eb;
    --primary-dark: #1e40af;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-700: #374151;
    --gray-900: #111827;
    --success: #10b981;
    --max-width: 1200px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
    line-height: 1.7;
    color: var(--gray-900);
    background: var(--gray-50);
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
.site-header {
    background: white;
    border-bottom: 2px solid var(--gray-100);
    padding: 20px 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 20px;
}

.site-title {
    font-size: 24px;
    font-weight: 700;
    color: var(--gray-900);
}

.main-nav {
    display: flex;
    gap: 30px;
}

.main-nav a {
    color: var(--gray-700);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

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

/* Main Content */
.main-content {
    padding: 60px 0;
}

/* Hero Section */
.hero {
    text-align: center;
    margin-bottom: 60px;
    padding: 40px 20px;
    background: white;
    border-radius: 12px;
}

.hero-title {
    font-size: 42px;
    font-weight: 800;
    color: var(--gray-900);
    margin-bottom: 16px;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 20px;
    color: var(--gray-700);
    max-width: 700px;
    margin: 0 auto;
}

/* Articles Grid */
.articles-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 30px;
    margin-bottom: 60px;
}

.article-card {
    background: white;
    border-radius: 12px;
    padding: 30px;
    transition: transform 0.2s, box-shadow 0.2s;
    border: 2px solid var(--gray-100);
}

.article-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.08);
}

.article-tag {
    display: inline-block;
    background: var(--primary);
    color: white;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 13px;
    font-weight: 600;
    margin-bottom: 16px;
}

.article-title {
    font-size: 22px;
    font-weight: 700;
    margin-bottom: 12px;
    line-height: 1.4;
}

.article-title a {
    color: var(--gray-900);
    text-decoration: none;
    transition: color 0.2s;
}

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

.article-excerpt {
    color: var(--gray-700);
    margin-bottom: 16px;
    font-size: 16px;
}

.article-meta {
    display: flex;
    gap: 20px;
    color: var(--gray-700);
    font-size: 14px;
    margin-bottom: 16px;
    padding-top: 16px;
    border-top: 1px solid var(--gray-100);
}

.article-link {
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
    font-size: 16px;
    transition: color 0.2s;
}

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

/* About Section */
.about-section {
    background: white;
    padding: 40px;
    border-radius: 12px;
    margin-bottom: 40px;
}

.about-section h2 {
    font-size: 28px;
    margin-bottom: 20px;
    color: var(--gray-900);
}

.about-section p {
    color: var(--gray-700);
    margin-bottom: 16px;
}

/* Footer */
.site-footer {
    background: white;
    border-top: 2px solid var(--gray-100);
    padding: 40px 0;
    text-align: center;
}

.site-footer p {
    color: var(--gray-700);
    margin-bottom: 8px;
}

.site-footer small {
    color: var(--gray-700);
    font-size: 13px;
}

/* Article Page Styles */
.article-header {
    max-width: 800px;
    margin: 0 auto 40px;
    text-align: center;
}

.article-header h1 {
    font-size: 40px;
    font-weight: 800;
    margin-bottom: 20px;
    line-height: 1.2;
    color: var(--gray-900);
}

.article-date {
    color: var(--gray-700);
    font-size: 15px;
}

.article-content {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    padding: 60px;
    border-radius: 12px;
    line-height: 1.8;
}

.article-content h2 {
    font-size: 32px;
    font-weight: 700;
    margin: 48px 0 20px 0;
    color: var(--gray-900);
}

.article-content h3 {
    font-size: 24px;
    font-weight: 600;
    margin: 36px 0 16px 0;
    color: var(--gray-900);
}

.article-content p {
    margin-bottom: 20px;
    color: var(--gray-700);
    font-size: 17px;
}

.article-content strong {
    color: var(--gray-900);
    font-weight: 600;
}

.article-content em {
    font-style: italic;
    color: var(--gray-700);
}

.article-content ul, 
.article-content ol {
    margin: 20px 0 20px 30px;
}

.article-content li {
    margin-bottom: 12px;
    color: var(--gray-700);
}

.article-content a {
    color: var(--primary);
    text-decoration: none;
    border-bottom: 1px solid var(--primary);
    transition: border-color 0.2s;
}

.article-content a:hover {
    border-bottom-color: var(--primary-dark);
}

.article-content code {
    background: var(--gray-100);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 15px;
    font-family: 'Courier New', monospace;
}

.article-content blockquote {
    border-left: 4px solid var(--primary);
    padding-left: 20px;
    margin: 24px 0;
    font-style: italic;
    color: var(--gray-700);
}

/* Related Articles */
.related-articles {
    max-width: 800px;
    margin: 60px auto 0;
    padding: 40px;
    background: var(--gray-50);
    border-radius: 12px;
}

.related-articles h2 {
    font-size: 24px;
    margin-bottom: 24px;
    color: var(--gray-900);
}

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

.related-articles li {
    margin-bottom: 16px;
}

.related-articles a {
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
    font-size: 17px;
}

.related-articles a:hover {
    text-decoration: underline;
}

/* Mobile Responsive */
@media (max-width: 768px) {
    .hero-title {
        font-size: 32px;
    }
    
    .hero-subtitle {
        font-size: 18px;
    }
    
    .articles-grid {
        grid-template-columns: 1fr;
    }
    
    .article-content {
        padding: 30px 20px;
    }
    
    .article-header h1 {
        font-size: 32px;
    }
    
    .main-nav {
        gap: 20px;
        width: 100%;
        justify-content: center;
    }
}

/* Performance: Reduce animations on slow connections */
@media (prefers-reduced-motion: reduce) {
    * {
        animation: none !important;
        transition: none !important;
    }
}