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

:root {
    --color-text: #1a1a1a;
    --color-text-secondary: #666;
    --color-text-light: #999;
    --color-bg: #ffffff;
    --color-bg-secondary: #f8f9fa;
    --color-border: #e0e0e0;
    --color-accent: #0066cc;
    --color-accent-hover: #0052a3;
    --color-link: #0066cc;
    --color-link-hover: #0052a3;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --max-width: 1200px;
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --border-radius: 8px;
    --transition: all 0.2s ease;
}

body {
    font-family: var(--font-family);
    color: var(--color-text);
    background-color: var(--color-bg);
    line-height: 1.6;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Header and Navigation */
.header {
    border-bottom: 1px solid var(--color-border);
    background-color: var(--color-bg);
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
    background-color: rgba(255, 255, 255, 0.9);
}

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

.logo {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-text);
    text-decoration: none;
    transition: var(--transition);
}

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

.nav-links {
    display: flex;
    gap: var(--spacing-lg);
}

.nav-link {
    color: var(--color-text-secondary);
    text-decoration: none;
    font-weight: 400;
    transition: var(--transition);
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-text);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    right: 0;
    height: 2px;
    background-color: var(--color-accent);
}

/* Main Content */
.main {
    min-height: calc(100vh - 200px);
    padding: var(--spacing-xl) 0;
}

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

.page-header {
    margin-bottom: var(--spacing-xl);
    text-align: center;
}

.page-title {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    letter-spacing: -0.02em;
}

.page-subtitle {
    font-size: 1.125rem;
    color: var(--color-text-secondary);
    font-weight: 400;
}

/* Articles Grid */
.articles-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
}

@media (min-width: 768px) {
    .articles-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 1024px) {
    .articles-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

.article-card {
    padding: var(--spacing-lg);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    background-color: var(--color-bg);
    transition: var(--transition);
    cursor: pointer;
}

.article-card:hover {
    border-color: var(--color-accent);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    transform: translateY(-2px);
}

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

.article-date {
    font-weight: 500;
}

.article-author {
    color: var(--color-text-secondary);
}

.article-title {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    line-height: 1.3;
}

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

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

.article-excerpt {
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-md);
    line-height: 1.6;
}

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

.tag {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background-color: var(--color-bg-secondary);
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--color-text-secondary);
}

/* Article Page Styles */
.article-page {
    max-width: 800px;
    margin: 0 auto;
    padding: var(--spacing-xl) var(--spacing-lg);
}

.article-header {
    margin-bottom: var(--spacing-xl);
}

.article-header .article-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    line-height: 1.2;
    letter-spacing: -0.02em;
}

.article-content {
    font-size: 1.125rem;
    line-height: 1.8;
    color: var(--color-text);
}

.article-content h2 {
    font-size: 2rem;
    font-weight: 600;
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-md);
    line-height: 1.3;
}

.article-content h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-top: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
}

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

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

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

.article-content code {
    background-color: var(--color-bg-secondary);
    padding: 0.2rem 0.4rem;
    border-radius: 4px;
    font-family: 'Monaco', 'Courier New', monospace;
    font-size: 0.9em;
}

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

.article-content pre code {
    background-color: transparent;
    padding: 0;
}

/* Interactive Visualization Container */
.viz-container {
    margin: var(--spacing-lg) 0;
    padding: var(--spacing-sm);
    background-color: var(--color-bg-secondary);
    border-radius: var(--border-radius);
    min-height: 300px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.viz-container svg {
    max-width: 100%;
    height: auto;
    display: block;
}

/* Ensure Venn diagram and other complex visualizations scale properly */
#venn-diagram {
    overflow: visible;
    width: 100%;
}

#venn-diagram svg {
    width: 100%;
    height: auto;
    max-width: 100%;
}

/* Comparison Table */
.comparison-table {
    width: 100%;
    border-collapse: collapse;
    margin: var(--spacing-lg) 0;
    font-size: 0.9rem;
    background-color: var(--color-bg);
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.comparison-table thead {
    background-color: var(--color-bg-secondary);
}

.comparison-table th,
.comparison-table td {
    padding: 0.75rem 1rem;
    text-align: left;
    border-bottom: 1px solid var(--color-border);
}

.comparison-table th {
    font-weight: 600;
    color: var(--color-text);
    white-space: nowrap;
}

.comparison-table tbody tr:hover {
    background-color: var(--color-bg-secondary);
}

.comparison-table tbody tr:last-child td {
    border-bottom: none;
}

/* Table cell alignment variants */
.comparison-table td.center,
.comparison-table th.center {
    text-align: center;
}

.comparison-table td.math {
    font-family: 'Times New Roman', serif;
}

/* Responsive table wrapper */
.table-wrapper {
    overflow-x: auto;
    margin: var(--spacing-lg) 0;
}

.table-caption {
    text-align: center;
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    margin-top: 0.5rem;
    margin-bottom: var(--spacing-lg);
    counter-increment: table-counter;
}

.table-caption::before {
    content: "Table " counter(table-counter) ". ";
    font-weight: bold;
}

/* Cross-reference links for figures and tables */
a.fig-ref,
a.tbl-ref {
    color: var(--color-link);
    text-decoration: none;
    border-bottom: 1px dotted var(--color-link);
}

a.fig-ref:hover,
a.tbl-ref:hover {
    border-bottom-style: solid;
}

/* Footer */
.footer {
    border-top: 1px solid var(--color-border);
    padding: var(--spacing-lg) 0;
    margin-top: var(--spacing-xl);
    background-color: var(--color-bg-secondary);
}

.footer-text {
    text-align: center;
    color: var(--color-text-secondary);
    font-size: 0.875rem;
}

.footer-text a {
    color: var(--color-link);
    text-decoration: none;
}

.footer-text a:hover {
    text-decoration: underline;
}

/* Figure Container for Images */
.figure-container {
    margin: var(--spacing-lg) 0;
    text-align: center;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

.figure-container img {
    max-width: 100%;
    height: auto;
    display: block;
    margin: 0 auto;
}

/* MathJax Formula Responsive Styles */
.MathJax {
    max-width: 100%;
    overflow-x: auto;
    overflow-y: hidden;
}

mjx-container {
    max-width: 100% !important;
    overflow-x: auto;
    overflow-y: hidden;
}

mjx-container[display="true"] {
    display: block;
    margin: 1em 0;
    text-align: center;
}

/* Allow horizontal scrolling for long formulas on mobile */
@media (max-width: 768px) {
    /* MathJax containers */
    .MathJax {
        overflow-x: auto;
        overflow-y: hidden;
        -webkit-overflow-scrolling: touch;
    }
    
    mjx-container {
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
        display: inline-block;
        max-width: 100%;
    }
    
    /* Wrap long inline math */
    .article-content p mjx-container {
        display: inline-block;
        max-width: 100%;
        vertical-align: middle;
        word-break: break-word;
    }
    
    /* Display math - allow horizontal scrolling */
    .article-content mjx-container[display="true"] {
        display: block;
        text-align: left;
        overflow-x: auto;
        padding: 0.5em 0;
        margin: 0.75em 0;
        -webkit-overflow-scrolling: touch;
    }
    
    /* Wrap paragraphs containing math to prevent overflow */
    .article-content p {
        overflow-wrap: break-word;
        word-wrap: break-word;
    }
    
    /* Ensure math doesn't break layout */
    .article-content p mjx-container,
    .article-content li mjx-container {
        max-width: calc(100% - 2em);
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .page-title {
        font-size: 2rem;
    }

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

    .nav-links {
        gap: var(--spacing-md);
    }

    .nav-container {
        padding: var(--spacing-sm) var(--spacing-md);
    }
    
    /* Article content adjustments */
    .article-content {
        font-size: 1rem;
        line-height: 1.7;
        overflow-wrap: break-word;
        word-wrap: break-word;
    }
    
    .article-content h2 {
        font-size: 1.5rem;
        margin-top: var(--spacing-lg);
    }
    
    .article-content h3 {
        font-size: 1.25rem;
    }
    
    /* Figure container adjustments */
    .figure-container {
        margin: var(--spacing-md) 0;
        padding: 0;
        width: 100%;
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }
    
    .figure-container img {
        width: 100% !important;
        max-width: 100% !important;
        height: auto !important;
        display: block;
        margin: 0 auto;
    }
    
    /* Ensure article page padding doesn't cause overflow */
    .article-page {
        padding: var(--spacing-lg) var(--spacing-md);
    }
    
    /* Visualization container adjustments */
    .viz-container {
        margin: var(--spacing-md) 0;
        padding: var(--spacing-xs);
        min-height: 200px;
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }
    
    /* Convert grid layouts to single column on mobile */
    .viz-container[style*="grid"] {
        display: block !important;
    }
    
    /* Override inline grid styles for mobile */
    div[style*="grid-template-columns"] {
        display: block !important;
        grid-template-columns: 1fr !important;
    }
    
    div[style*="grid-template-columns"] > * {
        margin-bottom: var(--spacing-sm);
    }
    
    /* Ensure SVG visualizations are responsive */
    .viz-container svg {
        max-width: 100%;
        height: auto;
        display: block;
    }
    
    /* Venn diagram specific mobile optimizations */
    #venn-diagram {
        overflow: visible;
        width: 100%;
        padding: 0;
    }
    
    #venn-diagram svg {
        width: 100%;
        height: auto;
        max-width: 100%;
    }
    
    /* Caption adjustments */
    .viz-caption {
        font-size: 0.85rem;
        margin-top: -0.25rem;
        margin-bottom: var(--spacing-md);
        padding: 0 var(--spacing-sm);
    }
    
    /* Code blocks */
    .article-content pre {
        font-size: 0.85rem;
        padding: var(--spacing-sm);
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }
    
    /* Tables */
    .table-wrapper {
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
        margin: var(--spacing-md) calc(-1 * var(--spacing-md));
        padding: 0 var(--spacing-md);
    }
    
    /* Prevent horizontal overflow */
    body {
        overflow-x: hidden;
    }
    
    .main {
        overflow-x: hidden;
    }
    
    /* Ensure all content respects container bounds */
    .article-content * {
        max-width: 100%;
    }
    
    /* Better spacing for mobile */
    .article-content p {
        margin-bottom: var(--spacing-sm);
    }
}

/* Utility Classes */
.text-center {
    text-align: center;
}

.mt-lg {
    margin-top: var(--spacing-lg);
}

.mb-lg {
    margin-bottom: var(--spacing-lg);
}

/* Footnotes */
.footnotes-separator {
    margin: 3rem 0 2rem;
    border: none;
    border-top: 1px solid var(--border-color);
}

.footnotes {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.footnotes h3 {
    font-size: 1.1rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.footnotes ol {
    padding-left: 1.5rem;
    margin: 0;
}

.footnotes li {
    margin-bottom: 0.75rem;
    line-height: 1.6;
}

.footnotes li:target {
    background-color: rgba(59, 130, 246, 0.1);
    padding: 0.25rem 0.5rem;
    margin-left: -0.5rem;
    border-radius: 4px;
}

.footnote-backref {
    margin-left: 0.5rem;
    text-decoration: none;
    color: var(--primary-color);
}

.footnote-backref:hover {
    text-decoration: underline;
}

/* Footnote references in text */
sup a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
}

sup a:hover {
    text-decoration: underline;
}

/* Side Notes (Margin Notes) */
.article-content {
    position: relative;
}

.sidenote {
    float: right;
    clear: right;
    margin-right: -45%;
    width: 40%;
    margin-top: 0.3rem;
    margin-bottom: 1rem;
    font-size: 0.85rem;
    line-height: 1.5;
    color: var(--text-secondary);
    padding-left: 1rem;
    border-left: 2px solid var(--border-color);
}

.sidenote-number {
    counter-increment: sidenote-counter;
}

.sidenote-number::after {
    content: counter(sidenote-counter);
    font-size: 0.75rem;
    top: -0.5rem;
    position: relative;
    color: var(--color-accent);
    font-weight: 600;
}

.sidenote::before {
    content: counter(sidenote-counter) ". ";
    font-weight: 600;
    color: var(--color-accent);
}

/* Reset counters at article level */
.article-content {
    counter-reset: sidenote-counter figure-counter table-counter;
}

/* Figure Caption with auto-increment */
.viz-caption {
    counter-increment: figure-counter;
    text-align: center;
    font-size: 0.9rem;
    color: var(--color-text-secondary);
    margin-top: -0.5rem;
    margin-bottom: var(--spacing-lg);
}

.viz-caption::before {
    content: "Figure " counter(figure-counter) ": ";
    font-weight: 600;
    color: var(--color-text);
}

/* Mobile: Show sidenotes inline */
@media (max-width: 1200px) {
    .sidenote {
        float: none;
        display: block;
        margin: 1rem 0;
        width: 100%;
        margin-right: 0;
        padding: 1rem;
        background-color: var(--color-bg-secondary);
        border-left: 3px solid var(--color-accent);
        border-radius: 0 var(--border-radius) var(--border-radius) 0;
    }
}

/* Toggle sidenote for mobile (optional clickable) */
.sidenote-toggle {
    display: none;
}

@media (max-width: 768px) {
    .sidenote-number {
        cursor: pointer;
    }
    
    .sidenote-toggle:not(:checked) + .sidenote {
        display: none;
    }
    
    .sidenote-toggle:checked + .sidenote {
        display: block;
    }
    
    .sidenote-toggle {
        display: none;
    }
}

/* ========================================
   Table of Contents (TOC) Navigation
   ======================================== */
.article-wrapper {
    display: flex;
    max-width: 1400px;
    margin: 0 auto;
    position: relative;
    padding: 0 var(--spacing-lg);
}

.article-wrapper .article-page {
    flex: 1;
    max-width: 800px;
    margin: 0;
    order: 2; /* Article comes after TOC */
}

.toc-nav {
    position: sticky;
    top: 100px;
    align-self: flex-start;
    width: 220px;
    min-width: 220px;
    margin-right: var(--spacing-xl);
    padding: var(--spacing-md);
    padding-right: var(--spacing-lg);
    max-height: calc(100vh - 150px);
    overflow-y: auto;
    order: 1; /* TOC comes first (left side) */
    border-right: 1px solid var(--color-border);
}

.toc-nav h4 {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-sm);
    text-align: right;
}

.toc-nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.toc-nav li {
    margin-bottom: 0.5rem;
}

.toc-nav a {
    display: block;
    padding: 0.35rem 0;
    padding-right: 0.75rem;
    font-size: 0.85rem;
    color: var(--color-text-secondary);
    text-decoration: none;
    border-right: 2px solid transparent;
    transition: all 0.2s ease;
    line-height: 1.4;
    text-align: right;
}

.toc-nav a:hover {
    color: var(--color-text);
    border-right-color: var(--color-border);
}

.toc-nav a.active {
    color: var(--color-accent);
    border-right-color: var(--color-accent);
    font-weight: 500;
}

/* Nested TOC items (h3) */
.toc-nav .toc-h3 {
    padding-right: 1.5rem;
    padding-left: 1rem;
    font-size: 0.8rem;
    color: var(--color-text-light);
    border-right-width: 1px;
}

.toc-nav .toc-h3::before {
    content: '→ ';
    font-size: 0.7rem;
    opacity: 0.6;
}

.toc-nav .toc-h3:hover {
    color: var(--color-text-secondary);
}

.toc-nav .toc-h3.active {
    color: var(--color-accent);
    border-right-color: var(--color-accent);
    font-weight: 400;
}

/* Hide TOC on smaller screens */
@media (max-width: 1100px) {
    .toc-nav {
        display: none;
    }
    
    .article-wrapper {
        display: block;
    }
    
    .article-wrapper .article-page {
        max-width: 800px;
        margin: 0 auto;
    }
}