:root {
    --color-text: #1e293b;
    --color-text-muted: #64748b;
    --color-text-light: #94a3b8;
    --color-bg: #ffffff;
    --color-bg-subtle: #f8fafc;
    --color-bg-code: #f1f5f9;
    --color-border: #e2e8f0;
    --color-primary: #3b82f6;
    --color-primary-dark: #1d4ed8;
    --color-success: #10b981;
    --color-warning: #f59e0b;
    --color-error: #ef4444;
    --font-sans: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'SF Mono', Consolas, 'Liberation Mono', Menlo, monospace;
    --content-width: 900px;
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
}

*, *::before, *::after {
    box-sizing: border-box;
}

body {
    font-family: var(--font-sans);
    font-size: 17px;
    line-height: 1.7;
    color: var(--color-text);
    background-color: var(--color-bg);
    margin: 0;
    padding: 0;
    -webkit-font-smoothing: antialiased;
}

.container {
    max-width: var(--content-width);
    margin: 0 auto;
    padding: var(--spacing-xl) var(--spacing-md);
}

article {
    padding: var(--spacing-2xl) 0;
}

h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.3;
    margin-top: var(--spacing-2xl);
    margin-bottom: var(--spacing-md);
    color: var(--color-text);
}

h1 {
    font-size: 2.25rem;
    margin-top: 0;
    margin-bottom: var(--spacing-lg);
}

h2 {
    font-size: 1.625rem;
    padding-bottom: var(--spacing-sm);
    border-bottom: 1px solid var(--color-border);
}

h3 {
    font-size: 1.25rem;
}

h4 {
    font-size: 1.1rem;
}

p {
    margin: 0 0 var(--spacing-lg) 0;
}

strong {
    font-weight: 600;
}

a {
    color: var(--color-primary);
    text-decoration: none;
    transition: color 0.15s ease;
}

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

/* === Lists === */
ul, ol {
    margin: 0 0 var(--spacing-lg) 0;
    padding-left: var(--spacing-lg);
}

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

li > ul, li > ol {
    margin-top: var(--spacing-sm);
    margin-bottom: 0;
}

code {
    font-family: var(--font-mono);
    font-size: 0.9em;
    background-color: var(--color-bg-code);
    padding: 0.15em 0.4em;
    border-radius: 4px;
    color: var(--color-text);
}

pre {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    line-height: 1.6;
    background-color: var(--color-bg-code);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: var(--spacing-md);
    margin: 0 0 var(--spacing-lg) 0;
    overflow-x: auto;
}

pre code {
    background: none;
    padding: 0;
    border-radius: 0;
    font-size: inherit;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin: 0 0 var(--spacing-lg) 0;
    font-size: 0.95rem;
}

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

th {
    font-weight: 600;
    background-color: var(--color-bg-subtle);
}

tr:hover {
    background-color: var(--color-bg-subtle);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
    margin: var(--spacing-lg) auto;
    border-radius: 8px;
}

figure {
    margin: var(--spacing-xl) 0;
}

figure img {
    margin: 0 auto var(--spacing-sm) auto;
}

figcaption {
    text-align: center;
    font-size: 0.9rem;
    color: var(--color-text-muted);
    font-style: italic;
}

blockquote {
    margin: 0 0 var(--spacing-lg) 0;
    padding: var(--spacing-md) var(--spacing-lg);
    border-left: 4px solid var(--color-primary);
    background-color: var(--color-bg-subtle);
    border-radius: 0 8px 8px 0;
}

blockquote p:last-child {
    margin-bottom: 0;
}

.callout {
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: 8px;
    margin: 0 0 var(--spacing-lg) 0;
}

.callout-info {
    background-color: #dbeafe;
    border: 1px solid #93c5fd;
}

.callout-warning {
    background-color: #fef3c7;
    border: 1px solid #fcd34d;
}

.callout-success {
    background-color: #dcfce7;
    border: 1px solid #86efac;
}

.callout-error {
    background-color: #fee2e2;
    border: 1px solid #fca5a5;
}

hr {
    border: none;
    height: 1px;
    background-color: var(--color-border);
    margin: var(--spacing-2xl) 0;
}

.post-meta {
    color: var(--color-text-muted);
    font-size: 0.95rem;
    margin-bottom: var(--spacing-xl);
}

.post-meta time {
    font-weight: 500;
}

.post-tags {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
    margin-top: var(--spacing-sm);
}

.tag {
    background-color: var(--color-bg-code);
    color: var(--color-text-muted);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: 4px;
    font-size: 0.85rem;
}

.toc {
    background-color: var(--color-bg-subtle);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.toc h2 {
    font-size: 1rem;
    margin: 0 0 var(--spacing-md) 0;
    padding: 0;
    border: none;
}

.toc ul {
    margin: 0;
    padding-left: var(--spacing-md);
}

.toc li {
    margin-bottom: var(--spacing-xs);
}

.diagram {
    margin: var(--spacing-xl) 0;
    padding: var(--spacing-md);
    background-color: var(--color-bg-subtle);
    border-radius: 8px;
    overflow-x: auto;
}

.diagram svg {
    display: block;
    margin: 0 auto;
    max-width: 100%;
    height: auto;
}

.hero {
    text-align: center;
    padding: var(--spacing-2xl) 0;
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-sm);
}

.hero .tagline {
    font-size: 1.2rem;
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-lg);
}

.hero .author {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-md);
}

.hero .avatar {
    width: 56px;
    height: 56px;
    border-radius: 50%;
    object-fit: cover;
    border: 2px solid var(--color-border);
    margin: 0 var(--spacing-xs);
}

.hero .author-info {
    text-align: left;
}

.hero .author-name {
    font-weight: 600;
    color: var(--color-text);
}

.hero .author-role {
    font-size: 0.9rem;
    color: var(--color-text-muted);
}

.social-links {
    margin-top: var(--spacing-lg);
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
}

.social-links a {
    color: var(--color-text-muted);
    padding: var(--spacing-sm);
    transition: color 0.15s ease;
}

.social-links a:hover {
    color: var(--color-primary);
}

.articles {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.article-card {
    padding: var(--spacing-lg);
    border: 1px solid var(--color-border);
    border-radius: 12px;
    transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.article-card:hover {
    border-color: var(--color-primary);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.article-card h2 {
    font-size: 1.35rem;
    margin: 0 0 var(--spacing-sm) 0;
    padding: 0;
    border: none;
}

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

.article-card h2 a:hover {
    color: var(--color-primary);
    text-decoration: none;
}

.article-card .meta {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-sm);
}

.article-card .excerpt {
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-md);
}

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

.featured {
    background: linear-gradient(135deg, #eff6ff, #f5f3ff);
    border-color: var(--color-primary);
}

.featured-badge {
    display: inline-block;
    background-color: var(--color-primary);
    color: white;
    font-size: 0.75rem;
    font-weight: 600;
    padding: 2px 8px;
    border-radius: 4px;
    margin-bottom: var(--spacing-sm);
}

.section-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.section-header h2 {
    margin: 0;
    padding: 0;
    border: none;
    font-size: 1.1rem;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.section-header::after {
    content: '';
    flex: 1;
    height: 1px;
    background-color: var(--color-border);
}

footer {
    margin-top: var(--spacing-2xl);
    padding: var(--spacing-xl) 0;
    border-top: 1px solid var(--color-border);
    text-align: center;
    color: var(--color-text-muted);
    font-size: 0.9rem;
}

@media (max-width: 640px) {
    body {
        font-size: 16px;
    }

    h1 {
        font-size: 1.75rem;
    }

    h2 {
        font-size: 1.375rem;
    }

    pre {
        font-size: 0.8rem;
        padding: var(--spacing-sm);
        border-radius: 6px;
    }

    table {
        font-size: 0.85rem;
    }

    th, td {
        padding: var(--spacing-xs) var(--spacing-sm);
    }
}

@media print {
    body {
        font-size: 12pt;
        line-height: 1.5;
    }

    .container {
        max-width: 100%;
    }

    a {
        color: inherit;
        text-decoration: underline;
    }

    pre, code {
        background-color: #f5f5f5 !important;
        border: 1px solid #ddd;
    }
}