* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #2b5cff;
    --primary-dark: #1e40d8;
    --primary-light: #5b83ff;
    --secondary-color: #0f172a;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-light: #667080;      /* 5.0:1 on white, 4.8:1 on --bg-secondary (WCAG AA) */
    --text-on-dark: #94a3b8;    /* footer text on the dark background */
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f1f5f9;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --transition: all 0.2s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
}

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

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

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

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Header */
.header {
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 72px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--secondary-color);
    letter-spacing: -0.5px;
    display: inline-flex;
    align-items: center;
}

.logo img {
    height: 38px;
    width: auto;
    display: block;
}

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

.nav-links {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-links a {
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    padding: 8px 0;
    position: relative;
}

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

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

/* Mobile nav toggle (shown below 768px) */
.nav-toggle {
    display: none;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 5px;
    width: 44px;
    height: 44px;
    padding: 0;
    border: 0;
    border-radius: var(--radius-md);
    background: transparent;
    cursor: pointer;
}
.nav-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    border-radius: 2px;
    background: var(--secondary-color);
    transition: var(--transition);
}
.nav-toggle:hover,
.nav-toggle:focus-visible {
    background: var(--bg-tertiary);
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* Main */
.main {
    padding: 48px 0;
}

/* Hero */
.hero {
    text-align: center;
    padding: 48px 0;
    margin-bottom: 24px;
}

.hero h1 {
    font-size: clamp(2.5rem, 5vw, 3.5rem);
    font-weight: 800;
    line-height: 1.2;
    color: var(--secondary-color);
    margin-bottom: 16px;
    letter-spacing: -1px;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* Post Cards */
.post-card {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 24px;
    transition: var(--transition);
}

.post-card:hover {
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-light);
    transform: translateY(-2px);
}

.post-card.featured {
    padding: 32px;
    border: 2px solid var(--primary-color);
}

.post-meta {
    display: flex;
    gap: 16px;
    margin-bottom: 12px;
    flex-wrap: wrap;
}

.category {
    background: var(--primary-color);
    color: white;
    padding: 4px 12px;
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.post-meta time {
    color: var(--text-light);
    font-size: 0.875rem;
}

.post-card h2,
.post-card h3 {
    font-size: 1.5rem;
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: 12px;
    color: var(--secondary-color);
}

.post-card h3 {
    font-size: 1.25rem;
}

.post-card h2 a:hover,
.post-card h3 a:hover {
    color: var(--primary-color);
}

.post-excerpt {
    color: var(--text-secondary);
    margin-bottom: 16px;
    line-height: 1.7;
}

.post-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 16px;
    border-top: 1px solid var(--border-color);
}

.author {
    color: var(--text-light);
    font-size: 0.875rem;
}

.read-more {
    font-weight: 600;
    font-size: 0.875rem;
    display: inline-flex;
    align-items: center;
    gap: 4px;
}

.read-more:hover {
    gap: 8px;
}

/* Featured Post */
.featured-post {
    margin-bottom: 48px;
}

/* Posts Grid */
.section-title {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--secondary-color);
    margin-bottom: 24px;
    padding-bottom: 12px;
    border-bottom: 2px solid var(--primary-color);
    display: inline-block;
}

.posts {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 24px;
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    gap: 8px;
    margin-top: 48px;
}

.page-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 44px;
    height: 44px;
    padding: 0 16px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-secondary);
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
}

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

.page-btn.active {
    cursor: default;
}

/* Sidebar */
.sidebar {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    padding: 48px 0;
}

.sidebar-widget {
    margin-bottom: 32px;
}

.sidebar-widget h3 {
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--secondary-color);
    margin-bottom: 16px;
    padding-bottom: 8px;
    border-bottom: 1px solid var(--border-color);
}

.category-list {
    list-style: none;
}

.category-list li {
    margin-bottom: 8px;
}

.category-list a {
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--text-secondary);
    font-size: 0.95rem;
    padding: 8px 0;
    border-bottom: 1px solid var(--border-color);
}

.category-list a:hover {
    color: var(--primary-color);
}

.category-list span {
    color: var(--text-light);
    font-size: 0.875rem;
    font-weight: 500;
}

.tag-cloud {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.tag {
    display: inline-block;
    padding: 6px 14px;
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    font-weight: 500;
    transition: var(--transition);
}

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

/* Newsletter */
.newsletter {
    background: var(--bg-primary);
    padding: 24px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
}

.newsletter p {
    color: var(--text-secondary);
    margin-bottom: 16px;
    font-size: 0.95rem;
}

.newsletter-form {
    display: flex;
    gap: 8px;
}

.newsletter-form input {
    flex: 1;
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 0.95rem;
    transition: var(--transition);
}

.newsletter-form input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.newsletter-form button {
    padding: 12px 20px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 0.95rem;
    cursor: pointer;
    transition: var(--transition);
}

.newsletter-form button:hover {
    background: var(--primary-dark);
}

/* Footer */
.footer {
    background: var(--secondary-color);
    color: var(--text-on-dark);
    padding: 48px 0 24px;
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr repeat(3, 1fr);
    gap: 48px;
    margin-bottom: 48px;
}

.footer-brand h3 {
    font-size: 1.5rem;
    font-weight: 700;
    color: white;
    margin-bottom: 12px;
}

.footer-brand p {
    line-height: 1.7;
}

.footer-column h4 {
    font-size: 1rem;
    font-weight: 600;
    color: white;
    margin-bottom: 16px;
}

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

.footer-column li {
    margin-bottom: 10px;
}

.footer-column a {
    color: var(--text-on-dark);
    font-size: 0.95rem;
}

.footer-column a:hover {
    color: var(--primary-light);
}

.footer-bottom {
    padding-top: 24px;
    border-top: 1px solid rgba(148, 163, 184, 0.2);
    text-align: center;
    font-size: 0.875rem;
}

.footer-bottom p + p {
    margin-top: 6px;
    opacity: 0.85;
}

/* ============ Article Pages - Rich Formatting ============ */
.reading-progress {
    position: fixed;
    top: 0;
    left: 0;
    height: 3px;
    width: 0%;
    background: linear-gradient(90deg, var(--primary-color), #8b5cf6, #06b6d4);
    z-index: 1000;
    transition: width 0.1s linear;
}

.article-full {
    max-width: 860px;
    margin: 0 auto;
    background: var(--bg-primary);
}

.article-hero-cover {
    border-radius: var(--radius-lg);
    padding: 40px 36px;
    margin-bottom: 32px;
    color: white;
    position: relative;
    overflow: hidden;
}
.article-hero-cover.cover-1 { background: linear-gradient(135deg, #1e3a8a 0%, #3b82f6 50%, #06b6d4 100%); }
.article-hero-cover.cover-2 { background: linear-gradient(135deg, #7c3aed 0%, #ec4899 60%, #f59e0b 100%); }
.article-hero-cover.cover-3 { background: linear-gradient(135deg, #065f46 0%, #059669 50%, #34d399 100%); }
.article-hero-cover.cover-4 { background: linear-gradient(135deg, #7c2d12 0%, #ea580c 50%, #facc15 100%); }
.article-hero-cover.cover-5 { background: linear-gradient(135deg, #0f172a 0%, #4c1d95 50%, #db2777 100%); }
.article-hero-cover .series-badge {
    display: inline-block;
    background: rgba(255,255,255,0.2);
    backdrop-filter: blur(8px);
    border: 1px solid rgba(255,255,255,0.3);
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 700;
    letter-spacing: 0.5px;
    text-transform: uppercase;
    margin-bottom: 16px;
}
.article-hero-cover .series-badge a {
    color: inherit;
    text-decoration: underline;
    text-decoration-color: rgba(255,255,255,0.6);
    text-underline-offset: 3px;
}
.article-hero-cover .series-badge a:hover { text-decoration-color: white; }
.article-hero-cover h1 {
    font-size: clamp(1.8rem, 4vw, 2.6rem);
    line-height: 1.2;
    font-weight: 800;
    letter-spacing: -0.5px;
    margin-bottom: 12px;
    color: white;
}
.article-hero-cover .article-subtitle {
    font-size: 1.1rem;
    opacity: 0.92;
    line-height: 1.6;
    max-width: 640px;
}

.article-header { margin-bottom: 8px; }
.article-meta {
    display: flex;
    align-items: center;
    gap: 12px;
    flex-wrap: wrap;
    margin-bottom: 16px;
    font-size: 0.875rem;
}
.article-meta time, .read-time, .difficulty {
    color: var(--text-secondary);
    display: inline-flex;
    align-items: center;
    gap: 6px;
}
.read-time {
    background: var(--bg-tertiary);
    padding: 4px 12px;
    border-radius: 20px;
    font-weight: 600;
}
.difficulty {
    background: #fef3c7;
    color: #92400e;
    padding: 4px 12px;
    border-radius: 20px;
    font-weight: 600;
}
.difficulty.advanced { background: #fee2e2; color: #991b1b; }
.difficulty.intermediate { background: #dbeafe; color: #1e40af; }

.article-author {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 16px 0;
    margin: 20px 0;
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}
.article-author > div { display: flex; flex-direction: column; }
.author-name { font-weight: 700; color: var(--secondary-color); }
.author-role { font-size: 0.875rem; color: var(--text-secondary); }

.key-takeaways {
    background: linear-gradient(180deg, #eff6ff, #dbeafe);
    border: 1px solid #bfdbfe;
    border-radius: var(--radius-lg);
    padding: 24px 28px;
    margin: 28px 0;
}
.key-takeaways h3 { color: #1e40af; margin-bottom: 12px; font-size: 1.05rem; }
.key-takeaways ul { margin-left: 20px; color: #1e3a8a; }
.key-takeaways li { margin-bottom: 8px; }

/* TOC */
.article-toc {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 24px 28px;
    margin: 28px 0 36px;
    position: relative;
}
.article-toc h3 {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-secondary);
    margin-bottom: 14px;
}
.article-toc ul { list-style: none; }
.article-toc li { margin-bottom: 6px; }
.article-toc a {
    color: var(--text-primary);
    font-size: 0.95rem;
    display: block;
    padding: 6px 12px;
    border-radius: var(--radius-sm);
    border-left: 3px solid transparent;
}
.article-toc a:hover, .article-toc a.toc-active {
    background: white;
    color: var(--primary-color);
    border-left-color: var(--primary-color);
}

/* Article body */
.article-content { font-size: 1.05rem; line-height: 1.8; color: #334155; }
.article-content section { margin-bottom: 48px; scroll-margin-top: 90px; }
.article-content h2 {
    font-size: 1.7rem;
    color: var(--secondary-color);
    margin: 0 0 16px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--border-color);
    letter-spacing: -0.3px;
    line-height: 1.3;
}
.article-content h3 {
    font-size: 1.25rem;
    color: var(--secondary-color);
    margin: 28px 0 12px;
}
.article-content h4 { font-size: 1.05rem; margin: 20px 0 8px; color: var(--secondary-color); }
.article-content p { margin-bottom: 16px; }
.article-content ul, .article-content ol { margin: 0 0 20px 24px; }
.article-content li { margin-bottom: 8px; }
.article-content li::marker { color: var(--primary-color); font-weight: 700; }
.article-content strong { color: var(--secondary-color); }
.article-content a { border-bottom: 1px dotted var(--primary-light); }

/* Code blocks */
.article-content pre {
    background: #0f172a;
    color: #e2e8f0;
    border-radius: var(--radius-md);
    padding: 20px 22px;
    overflow-x: auto;
    margin: 20px 0;
    font-size: 0.87rem;
    line-height: 1.6;
    position: relative;
    border: 1px solid #1e293b;
    box-shadow: var(--shadow-md);
}
.article-content pre code {
    font-family: 'Cascadia Code', 'Fira Code', Consolas, 'Courier New', monospace;
    background: transparent;
    padding: 0;
    color: inherit;
}
.article-content :not(pre) > code {
    background: #f1f5f9;
    color: #be123c;
    padding: 2px 8px;
    border-radius: 6px;
    font-size: 0.88em;
    font-family: 'Cascadia Code', Consolas, monospace;
    border: 1px solid var(--border-color);
    white-space: nowrap;
}
.code-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: #1e293b;
    color: #94a3b8;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.8px;
    padding: 8px 16px;
    border-radius: var(--radius-md) var(--radius-md) 0 0;
    margin-bottom: -20px;
    margin-top: 20px;
    position: relative;
    z-index: 1;
}
.code-header + pre { border-top-left-radius: 0; border-top-right-radius: 0; }
.copy-btn {
    background: rgba(255,255,255,0.1);
    border: 1px solid rgba(255,255,255,0.2);
    color: #e2e8f0;
    padding: 4px 12px;
    border-radius: 6px;
    font-size: 0.75rem;
    cursor: pointer;
    transition: var(--transition);
}
.copy-btn:hover { background: var(--primary-color); border-color: var(--primary-color); color: white; }

/* Callouts */
.callout {
    border-radius: var(--radius-md);
    padding: 18px 22px;
    margin: 24px 0;
    border-left: 4px solid;
    font-size: 0.97rem;
    line-height: 1.7;
}
.callout strong { display: block; margin-bottom: 4px; }
.callout-info { background: #eff6ff; border-color: #3b82f6; color: #1e40af; }
.callout-warning { background: #fffbeb; border-color: #f59e0b; color: #92400e; }
.callout-success { background: #ecfdf5; border-color: #10b981; color: #065f46; }
.callout-danger { background: #fef2f2; border-color: #ef4444; color: #991b1b; }
.callout-tip { background: #f5f3ff; border-color: #8b5cf6; color: #5b21b6; }

/* Chat examples */
.chat-example {
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    overflow: hidden;
    margin: 24px 0;
    box-shadow: var(--shadow-sm);
}
.chat-user {
    background: #f8fafc;
    padding: 16px 22px;
    border-bottom: 1px solid var(--border-color);
    font-size: 0.97rem;
}
.chat-assistant {
    background: white;
    padding: 18px 22px;
    font-size: 0.97rem;
}
.chat-assistant pre { margin: 14px 0; }
.chat-user strong { color: var(--primary-color); }
.chat-assistant strong { color: var(--secondary-color); }

/* Architecture diagrams */
.architecture-diagram {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    flex-wrap: wrap;
    background: var(--bg-secondary);
    border: 1px dashed var(--border-color);
    border-radius: var(--radius-lg);
    padding: 28px 20px;
    margin: 24px 0;
}
.flow-step {
    background: white;
    border: 2px solid var(--primary-color);
    color: var(--secondary-color);
    font-weight: 700;
    font-size: 0.9rem;
    padding: 12px 20px;
    border-radius: 10px;
    box-shadow: var(--shadow-sm);
    text-align: center;
}
.flow-arrow { font-size: 1.4rem; color: var(--primary-color); font-weight: 800; }
.flow-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 8px;
    width: 100%;
    margin-top: 12px;
}
.flow-grid .flow-step { border-color: #8b5cf6; font-size: 0.85rem; padding: 10px 12px; }

/* Tables */
.requirements-table, .result-table {
    width: 100%;
    border-collapse: collapse;
    margin: 20px 0;
    font-size: 0.93rem;
    background: white;
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}
.requirements-table th, .result-table th {
    background: var(--secondary-color);
    color: white;
    text-align: left;
    padding: 12px 16px;
    font-weight: 600;
}
.requirements-table td, .result-table td {
    padding: 12px 16px;
    border-bottom: 1px solid var(--border-color);
}
.requirements-table tr:last-child td, .result-table tr:last-child td { border-bottom: none; }
.requirements-table tr:nth-child(even) td, .result-table tr:nth-child(even) td { background: #f8fafc; }
.status-success { background: #dcfce7; color: #166534; padding: 3px 10px; border-radius: 12px; font-weight: 700; font-size: 0.8rem; }
.status-warning { background: #fef3c7; color: #92400e; padding: 3px 10px; border-radius: 12px; font-weight: 700; font-size: 0.8rem; }
.status-error { background: #fee2e2; color: #991b1b; padding: 3px 10px; border-radius: 12px; font-weight: 700; font-size: 0.8rem; }

/* Series nav + buttons */
.series-progress {
    display: flex;
    gap: 6px;
    margin: 16px 0 24px;
}
.series-progress .dot {
    flex: 1;
    height: 6px;
    border-radius: 3px;
    background: var(--border-color);
}
.series-progress .dot.done { background: var(--primary-color); }
.series-progress .dot.current { background: linear-gradient(90deg, var(--primary-color), #8b5cf6); }

.article-navigation {
    display: flex;
    justify-content: space-between;
    gap: 16px;
    margin-top: 36px;
    padding-top: 28px;
    border-top: 2px solid var(--border-color);
    flex-wrap: wrap;
}
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 26px;
    border-radius: var(--radius-md);
    font-weight: 700;
    font-size: 0.95rem;
    transition: var(--transition);
    border: 1px solid transparent;
    font-family: inherit;
    cursor: pointer;
}
.btn-primary { background: var(--primary-color); color: white; }
.btn-primary:hover { background: var(--primary-dark); color: white; transform: translateY(-1px); box-shadow: var(--shadow-md); }
.btn-secondary { background: white; color: var(--text-primary); border-color: var(--border-color); }
.btn-secondary:hover { border-color: var(--primary-color); color: var(--primary-color); }
.btn-sm { padding: 10px 18px; font-size: 0.85rem; }

/* Replaces former inline style attributes (kept out of markup so CSP style-src can stay 'self') */
.section-spaced { margin-top: 40px; }
.posts-tight { margin-top: 16px; }
.follow-links { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 12px; }

.article-footer { margin-top: 40px; padding-top: 24px; border-top: 1px solid var(--border-color); }
.article-tags { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; margin-bottom: 14px; }
.article-series {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 14px 18px;
    font-size: 0.92rem;
    color: var(--text-secondary);
}
.series-list { list-style: none; margin: 12px 0 0 0 !important; }
.series-list li { margin-bottom: 6px; font-size: 0.92rem; }
.series-list a { font-weight: 600; }
.series-list .current-part { color: var(--secondary-color); font-weight: 700; }

.checklist { list-style: none !important; margin-left: 0 !important; }
.checklist li { padding-left: 32px; position: relative; }
.checklist li::before { content: '☐'; position: absolute; left: 4px; color: var(--primary-color); font-weight: 800; }

.back-to-series {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 20px;
    color: var(--text-secondary);
}
.back-to-series:hover { color: var(--primary-color); }

/* Series cards on homepage */
.series-banner {
    background: linear-gradient(135deg, #0f172a 0%, #1e3a8a 50%, #7c3aed 100%);
    color: white;
    border-radius: var(--radius-lg);
    padding: 40px 36px;
    margin-bottom: 32px;
    position: relative;
    overflow: hidden;
}
.series-banner::after {
    content: '';
    position: absolute;
    top: -60px; right: -60px;
    width: 220px; height: 220px;
    background: radial-gradient(circle, rgba(255,255,255,0.15), transparent);
    border-radius: 50%;
}
.series-banner h2 { color: white; font-size: 1.8rem; margin-bottom: 10px; }
.series-banner p { opacity: 0.9; max-width: 620px; margin-bottom: 20px; }
.series-parts { display: flex; gap: 10px; flex-wrap: wrap; }
.series-parts a {
    background: rgba(255,255,255,0.15);
    border: 1px solid rgba(255,255,255,0.25);
    color: white;
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}
.series-parts a:hover { background: white; color: #1e3a8a; }

.post-card .part-number {
    display: inline-block;
    background: linear-gradient(135deg, var(--primary-color), #8b5cf6);
    color: white;
    font-size: 0.75rem;
    font-weight: 800;
    padding: 4px 12px;
    border-radius: 20px;
    margin-bottom: 10px;
    letter-spacing: 0.5px;
}

/* Responsive */
@media (max-width: 1024px) {
    .footer-content {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 768px) {
    .nav-toggle {
        display: flex;
    }

    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        flex-direction: column;
        gap: 0;
        padding: 4px 24px 12px;
        background: var(--bg-primary);
        border-bottom: 1px solid var(--border-color);
        box-shadow: var(--shadow-lg);
    }

    .nav-links.is-open {
        display: flex;
    }

    .nav-links a {
        display: block;
        padding: 14px 0;
        font-size: 1.05rem;
        border-bottom: 1px solid var(--border-color);
    }

    .nav-links li:last-child a {
        border-bottom: 0;
    }

    .nav-links a.active::after {
        display: none;
    }

    .hero {
        padding: 32px 0;
    }

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

    .post-card.featured {
        padding: 24px;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .sidebar {
        padding-top: 0;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 16px;
    }

    .nav {
        height: 60px;
    }

    .nav-links {
        padding: 4px 16px 12px;
    }

    .logo {
        font-size: 1.25rem;
    }

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

    .hero-subtitle {
        font-size: 1rem;
    }

    .section-title {
        font-size: 1.5rem;
    }

    .pagination {
        flex-wrap: wrap;
    }

    .article-hero-cover { padding: 28px 22px; }
    .article-content { font-size: 1rem; }
    .article-content h2 { font-size: 1.4rem; }
    .article-navigation { flex-direction: column; }
    .article-navigation .btn { justify-content: center; }
    .flow-grid { grid-template-columns: 1fr 1fr; }
    .requirements-table, .result-table { font-size: 0.85rem; display: block; overflow-x: auto; }
    .series-banner { padding: 28px 22px; }
}