/* Base Styles */
:root {
    /* Color Variables */
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --accent-color: #f59e0b;
    --text-color: #1f2937;
    --text-light: #6b7280;
    --background-color: #ffffff;
    --background-alt: #f3f4f6;
    --border-color: #e5e7eb;
    --code-background: #282c34;
    --code-text: #f8f8f2;
    --success-color: #10b981;
    --error-color: #ef4444;
    --warning-color: #f59e0b;
    
    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'Fira Code', 'Consolas', 'Monaco', 'Andale Mono', monospace;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Container widths */
    --container-sm: 640px;
    --container-md: 768px;
    --container-lg: 1024px;
    --container-xl: 1280px;
    
    /* Border radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.375rem;
    --radius-lg: 0.5rem;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
    --transition-slow: 500ms ease;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

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

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

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

img, picture, video, canvas, svg {
    display: block;
    max-width: 100%;
}

input, button, textarea, select {
    font: inherit;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
    font-weight: 700;
}

h1 {
    font-size: 2.5rem;
}

h2 {
    font-size: 2rem;
}

h3 {
    font-size: 1.5rem;
}

h4 {
    font-size: 1.25rem;
}

h5 {
    font-size: 1.125rem;
}

h6 {
    font-size: 1rem;
}

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

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

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

ul, ol {
    margin-bottom: var(--spacing-md);
    padding-left: var(--spacing-lg);
}

/* Container */
.container {
    width: 100%;
    max-width: var(--container-xl);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    font-weight: 600;
    text-align: center;
    text-decoration: none;
    cursor: pointer;
    transition: all var(--transition-fast);
    border: none;
}

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

.btn.primary:hover {
    background-color: var(--secondary-color);
    text-decoration: none;
}

.btn.secondary {
    background-color: var(--background-alt);
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

.btn.secondary:hover {
    background-color: var(--border-color);
    text-decoration: none;
}

.btn.tertiary {
    background-color: transparent;
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

.btn.tertiary:hover {
    background-color: var(--background-alt);
    text-decoration: none;
}

/* Header */
header {
    background-color: var(--background-color);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
    padding: var(--spacing-md) 0;
}

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

.logo a {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-color);
    text-decoration: none;
}

.main-nav {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
}

.main-nav li {
    margin-left: var(--spacing-md);
}

.main-nav a {
    color: var(--text-color);
    font-weight: 500;
    text-decoration: none;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.main-nav a:hover {
    background-color: var(--background-alt);
    color: var(--primary-color);
    text-decoration: none;
}

.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
}

.mobile-menu-toggle span {
    display: block;
    width: 25px;
    height: 3px;
    background-color: var(--text-color);
    margin: 5px 0;
    transition: all var(--transition-fast);
}

/* Hero Section */
.hero {
    padding: var(--spacing-3xl) 0;
    background-color: var(--background-alt);
    text-align: center;
}

.hero h1 {
    margin-bottom: var(--spacing-lg);
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.hero p {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-xl);
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.cta-buttons {
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
}

/* Featured Examples */
.featured-examples {
    padding: var(--spacing-3xl) 0;
}

.featured-examples h2 {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.examples-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--spacing-lg);
}

.example-card {
    background-color: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-normal);
}

.example-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

.example-card h3 {
    margin-bottom: var(--spacing-sm);
}

.example-card .read-more {
    margin-top: var(--spacing-md);
    display: inline-block;
    font-weight: 600;
}

/* Categories */
.categories {
    padding: var(--spacing-3xl) 0;
    background-color: var(--background-alt);
}

.categories h2 {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.category-card {
    background-color: var(--background-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
}

.category-card h3 {
    margin-bottom: var(--spacing-md);
    border-bottom: 2px solid var(--primary-color);
    padding-bottom: var(--spacing-xs);
}

.category-card ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

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

.category-card a {
    display: block;
    padding: var(--spacing-xs) 0;
    transition: all var(--transition-fast);
}

.category-card a:hover {
    transform: translateX(5px);
}

/* Interactive Demo */
.interactive-demo {
    padding: var(--spacing-3xl) 0;
}

.interactive-demo h2 {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.code-editor-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
    background-color: var(--code-background);
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-md);
}

.code-editor {
    padding: var(--spacing-md);
}

.code-editor textarea {
    width: 100%;
    height: 400px;
    background-color: var(--code-background);
    color: var(--code-text);
    border: none;
    font-family: var(--font-mono);
    resize: none;
    outline: none;
    padding: var(--spacing-md);
    font-size: 0.9rem;
    line-height: 1.6;
}

.preview {
    background-color: white;
}

.preview iframe {
    width: 100%;
    height: 400px;
    border: none;
}

.editor-controls {
    grid-column: 1 / -1;
    display: flex;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background-color: var(--background-alt);
}

.demo-note {
    text-align: center;
    font-style: italic;
}

/* Latest Articles */
.latest-articles {
    padding: var(--spacing-3xl) 0;
    background-color: var(--background-alt);
}

.latest-articles h2 {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.articles-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.article-card {
    background-color: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
}

.article-card h3 {
    margin-bottom: var(--spacing-xs);
}

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

.view-all {
    text-align: center;
}

/* Footer */
footer {
    background-color: var(--text-color);
    color: white;
    padding: var(--spacing-2xl) 0 var(--spacing-md);
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

.footer-column h4 {
    color: white;
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-xs);
    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
}

.footer-column ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

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

.footer-column a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
}

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

.footer-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--spacing-md);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    font-size: 0.9rem;
}

.footer-links {
    display: flex;
    gap: var(--spacing-md);
    list-style: none;
    padding: 0;
    margin: 0;
}

/* Code Syntax Highlighting */
.code-block {
    background-color: var(--code-background);
    color: var(--code-text);
    font-family: var(--font-mono);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-md);
    overflow-x: auto;
    position: relative;
}

.code-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: rgba(0, 0, 0, 0.2);
    border-top-left-radius: var(--radius-md);
    border-top-right-radius: var(--radius-md);
    font-size: 0.9rem;
}

.copy-button {
    background-color: transparent;
    border: 1px solid rgba(255, 255, 255, 0.2);
    color: rgba(255, 255, 255, 0.8);
    padding: 2px 8px;
    font-size: 0.8rem;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.copy-button:hover {
    background-color: rgba(255, 255, 255, 0.1);
    color: white;
}

/* Media Queries */
@media (max-width: 1024px) {
    h1 {
        font-size: 2.25rem;
    }
    
    h2 {
        font-size: 1.75rem;
    }
    
    .code-editor-container {
        grid-template-columns: 1fr;
    }
    
    .code-editor textarea, .preview iframe {
        height: 300px;
    }
}

@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }
    
    h2 {
        font-size: 1.5rem;
    }
    
    .mobile-menu-toggle {
        display: block;
    }
    
    .main-nav {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        flex-direction: column;
        background-color: var(--background-color);
        box-shadow: var(--shadow-md);
        padding: var(--spacing-md);
    }
    
    .main-nav.active {
        display: flex;
    }
    
    .main-nav li {
        margin: 0;
        margin-bottom: var(--spacing-sm);
    }
    
    .main-nav a {
        display: block;
        padding: var(--spacing-sm);
    }
    
    .cta-buttons {
        flex-direction: column;
    }
    
    .footer-bottom {
        flex-direction: column;
        gap: var(--spacing-md);
        text-align: center;
    }
    
    .footer-links {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    h1 {
        font-size: 1.75rem;
    }
    
    h2 {
        font-size: 1.25rem;
    }
    
    .hero {
        padding: var(--spacing-xl) 0;
    }
    
    .featured-examples, .categories, .interactive-demo, .latest-articles {
        padding: var(--spacing-xl) 0;
    }
}
/* ==========================================================================
   Site chrome additions
   ========================================================================== */

/* Skip link — visible only once it receives keyboard focus. */
.skip-link {
    position: absolute;
    left: var(--spacing-md);
    top: var(--spacing-md);
    z-index: 200;
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--primary-color);
    color: #fff;
    border-radius: var(--radius-md);
    font-weight: 600;
    transform: translateY(-200%);
    transition: transform var(--transition-fast);
}

.skip-link:focus {
    transform: translateY(0);
    color: #fff;
    text-decoration: none;
}

/* A single, consistent focus ring for every interactive element. */
:where(a, button, input, textarea, select, summary, [tabindex]):focus-visible {
    outline: 3px solid var(--primary-color);
    outline-offset: 2px;
    border-radius: var(--radius-sm);
}

/* Headings targeted by an in-page link get focus programmatically; don't ring them. */
:where(section, h2, h3)[tabindex="-1"]:focus {
    outline: none;
}

/* The nav carries twelve items — let it wrap rather than overflow. */
.main-nav {
    flex-wrap: wrap;
    justify-content: flex-end;
    row-gap: var(--spacing-xs);
}

.main-nav a {
    font-size: 0.9375rem;
}

.main-nav a[aria-current="page"] {
    color: var(--primary-color);
    background-color: var(--background-alt);
}

header .container {
    gap: var(--spacing-md);
}

/* ==========================================================================
   Page shell: header block, breadcrumbs, two-column content
   ========================================================================== */

.page-header {
    background-color: var(--background-alt);
    border-bottom: 1px solid var(--border-color);
    padding: var(--spacing-xl) 0;
}

.page-header h1 {
    margin-bottom: var(--spacing-sm);
}

.lead,
.section-intro {
    font-size: 1.125rem;
    color: var(--text-light);
    max-width: 68ch;
}

.breadcrumbs {
    margin-bottom: var(--spacing-md);
    font-size: 0.875rem;
}

.breadcrumbs ul,
.breadcrumbs ol {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    list-style: none;
    padding: 0;
    margin: 0;
}

.breadcrumbs li + li::before {
    content: "/";
    margin-right: var(--spacing-sm);
    color: var(--text-light);
}

.breadcrumbs [aria-current="page"] {
    color: var(--text-light);
}

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

.content-grid,
.content-wrapper {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 300px;
    gap: var(--spacing-2xl);
    align-items: start;
}

/* Pages without a sidebar shouldn't leave a 300px gutter. */
.content-grid:not(:has(.sidebar)),
.content-wrapper:not(:has(.sidebar)) {
    grid-template-columns: minmax(0, 1fr);
    max-width: 80ch;
}

.main-content,
.main-article,
.page-content {
    min-width: 0;
}

.main-content > section,
.main-article > section {
    margin-bottom: var(--spacing-2xl);
    scroll-margin-top: 6rem;
}

.main-content h2,
.main-article h2 {
    margin-top: var(--spacing-xl);
    padding-bottom: var(--spacing-xs);
    border-bottom: 1px solid var(--border-color);
}

.main-content h3,
.main-article h3 {
    margin-top: var(--spacing-lg);
}

.full-width {
    grid-column: 1 / -1;
}

/* Anything with an id can be an in-page link target. */
[id] {
    scroll-margin-top: 6rem;
}

/* ==========================================================================
   Table of contents & sidebar
   ========================================================================== */

.table-of-contents {
    background-color: var(--background-alt);
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--primary-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.table-of-contents h2 {
    font-size: 1.125rem;
    margin: 0 0 var(--spacing-sm);
    border: none;
    padding: 0;
}

.table-of-contents ul {
    list-style: none;
    padding: 0;
    margin: 0;
    columns: 2;
    column-gap: var(--spacing-xl);
}

.table-of-contents li {
    margin-bottom: var(--spacing-xs);
    break-inside: avoid;
}

.sidebar {
    position: sticky;
    top: 6rem;
    display: grid;
    gap: var(--spacing-lg);
}

.sidebar-widget,
.cta-widget,
.newsletter {
    background-color: var(--background-alt);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
}

.sidebar-widget h3,
.cta-widget h3 {
    font-size: 1.0625rem;
    margin-bottom: var(--spacing-sm);
    padding-bottom: var(--spacing-xs);
    border-bottom: 1px solid var(--border-color);
}

.sidebar-links,
.resources-list,
.related-topics ul,
.related-pages ul,
.sidebar-widget ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.sidebar-links li,
.resources-list li,
.sidebar-widget li {
    margin-bottom: var(--spacing-xs);
    font-size: 0.9375rem;
}

.sidebar-links li.active > a {
    font-weight: 700;
    color: var(--secondary-color);
}

/* ==========================================================================
   Code examples
   ========================================================================== */

.code-example,
.code-container,
.code-snippet,
.mini-example {
    position: relative;
    margin-bottom: var(--spacing-lg);
}

.code-example > .code-block,
.code-container > .code-block {
    margin-bottom: 0;
}

/* Blocks that aren't wrapped in .code-block still need the dark treatment. */
.code-example > pre,
.code-container > pre,
.code-snippet > pre,
.mini-example > pre {
    background-color: var(--code-background);
    color: var(--code-text);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    overflow-x: auto;
}

.code-block pre,
.code-example pre,
.code-container pre {
    margin: 0;
    overflow-x: auto;
}

.code-block code,
.code-example code,
.code-container code {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    line-height: 1.7;
    white-space: pre;
}

/* Inline code inside prose. */
:where(p, li, td, dd, h3, h4) > code {
    background-color: var(--background-alt);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: 0.1em 0.35em;
    font-family: var(--font-mono);
    font-size: 0.875em;
    word-break: break-word;
}

.code-example > .copy-button,
.code-container > .copy-button,
.code-snippet > .copy-button {
    position: absolute;
    top: var(--spacing-sm);
    right: var(--spacing-sm);
    background-color: rgba(255, 255, 255, 0.1);
}

.copy-button.is-error {
    border-color: var(--error-color);
    color: var(--error-color);
}

.code-explanation {
    background-color: var(--background-alt);
    border: 1px solid var(--border-color);
    border-top: none;
    border-radius: 0 0 var(--radius-md) var(--radius-md);
    padding: var(--spacing-md);
    font-size: 0.9375rem;
}

.code-explanation :last-child {
    margin-bottom: 0;
}

/* Do / don't pairs. */
.code-good,
.code-bad {
    border-left: 4px solid;
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.code-good {
    border-left-color: var(--success-color);
    background-color: rgba(16, 185, 129, 0.06);
}

.code-bad {
    border-left-color: var(--error-color);
    background-color: rgba(239, 68, 68, 0.06);
}

.code-good > pre,
.code-bad > pre {
    background-color: var(--code-background);
    color: var(--code-text);
    border-radius: var(--radius-sm);
    padding: var(--spacing-md);
    overflow-x: auto;
}

/* ==========================================================================
   Callouts
   ========================================================================== */

.note,
.tip,
.note-box,
.info-box,
.warning-box,
.key-facts {
    border-left: 4px solid var(--primary-color);
    background-color: var(--background-alt);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    padding: var(--spacing-md) var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.note :last-child,
.tip :last-child,
.note-box :last-child,
.info-box :last-child,
.warning-box :last-child,
.key-facts :last-child {
    margin-bottom: 0;
}

.tip {
    border-left-color: var(--success-color);
    background-color: rgba(16, 185, 129, 0.07);
}

.warning-box {
    border-left-color: var(--warning-color);
    background-color: rgba(245, 158, 11, 0.09);
}

.key-facts {
    border-left-color: var(--accent-color);
}

.note h3, .note h4,
.tip h3, .tip h4,
.info-box h3, .info-box h4,
.warning-box h3, .warning-box h4,
.key-facts h3, .key-facts h4 {
    margin-top: 0;
    font-size: 1.0625rem;
}

/* ==========================================================================
   Card grids
   ========================================================================== */

.category-cards,
.guides-grid,
.challenges-list,
.community-gallery,
.next-steps-grid,
.examples-cards,
.contact-options,
.mini-examples,
.element-examples {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(min(100%, 280px), 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.guide-card,
.challenge-card,
.community-example,
.next-step-card,
.cta-card,
.contact-option,
.template-features,
.resource-group,
.faq-item,
.sitemap-section,
.element-reference,
.testimonial {
    background-color: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
}

.guide-card h3,
.challenge-card h3,
.community-example h3,
.next-step-card h3,
.faq-item h2,
.sitemap-section h2 {
    margin-top: 0;
    font-size: 1.1875rem;
    border: none;
    padding: 0;
}

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

.faq-item :last-child {
    margin-bottom: 0;
}

.sitemap-section,
.resource-group {
    margin-bottom: var(--spacing-lg);
}

.resource-group ul,
.sitemap-section ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.resource-group li,
.sitemap-section li {
    padding: var(--spacing-xs) 0;
    border-bottom: 1px solid var(--border-color);
}

.resource-group li:last-child,
.sitemap-section li:last-child {
    border-bottom: none;
}

.cta-box,
.submit-cta,
.thank-you,
.practice-section {
    background-color: var(--background-alt);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    text-align: center;
}

.cta-box h3,
.submit-cta h3 {
    margin-top: 0;
}

/* Difficulty badges. */
.level-icon,
.element-type,
.beginner,
.intermediate,
.advanced {
    display: inline-block;
    padding: 0.15em 0.6em;
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.03em;
}

.beginner  { background-color: rgba(16, 185, 129, 0.15); color: #047857; }
.intermediate { background-color: rgba(245, 158, 11, 0.18); color: #92400e; }
.advanced  { background-color: rgba(239, 68, 68, 0.15);  color: #b91c1c; }

/* ==========================================================================
   Lists that read as checklists
   ========================================================================== */

.check-list,
.checklist ul,
.tips-list,
.mistake-list,
.shortcuts-list {
    list-style: none;
    padding-left: 0;
}

.check-list li,
.checklist ul li,
.tips-list li {
    position: relative;
    padding-left: 1.75rem;
    margin-bottom: var(--spacing-sm);
}

.check-list li::before,
.checklist ul li::before,
.tips-list li::before {
    content: "\2713";
    position: absolute;
    left: 0;
    color: var(--success-color);
    font-weight: 700;
}

.mistake-list li {
    position: relative;
    padding-left: 1.75rem;
    margin-bottom: var(--spacing-sm);
}

.mistake-list li::before {
    content: "\00d7";
    position: absolute;
    left: 0;
    color: var(--error-color);
    font-weight: 700;
    font-size: 1.2em;
    line-height: 1;
}

/* ==========================================================================
   Tables
   ========================================================================== */

.table-responsive,
.data-table {
    overflow-x: auto;
    margin-bottom: var(--spacing-lg);
}

table {
    border-collapse: collapse;
    width: 100%;
    font-size: 0.9375rem;
}

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

thead th {
    background-color: var(--background-alt);
    font-weight: 700;
}

tbody tr:nth-child(even) {
    background-color: var(--background-alt);
}

caption {
    caption-side: bottom;
    padding-top: var(--spacing-sm);
    color: var(--text-light);
    font-size: 0.875rem;
    text-align: left;
}

/* ==========================================================================
   Live editor extras
   ========================================================================== */

.preview-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--background-alt);
    border-bottom: 1px solid var(--border-color);
    font-size: 0.875rem;
    font-weight: 600;
}

.device-selector,
.level-buttons,
.alphabet-links {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.device-button,
.level-button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    background: none;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: var(--spacing-xs) var(--spacing-sm);
    color: var(--text-light);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.device-button:hover,
.level-button:hover {
    color: var(--primary-color);
    border-color: var(--primary-color);
}

.device-button.active,
.level-button.active {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
    color: #fff;
}

.preview iframe {
    transition: width var(--transition-normal);
    margin: 0 auto;
}

.alphabet-links a {
    display: inline-block;
    min-width: 2rem;
    padding: var(--spacing-xs);
    text-align: center;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-weight: 600;
}

.search-box,
.element-search {
    margin-bottom: var(--spacing-lg);
}

.search-box input,
.element-search input {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background-color: var(--background-color);
    color: var(--text-color);
}

/* ==========================================================================
   Element reference blocks
   ========================================================================== */

.element-header {
    display: flex;
    flex-wrap: wrap;
    align-items: baseline;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
}

.element-syntax,
.element-attributes,
.element-accessibility,
.element-compatibility,
.element-best-practices,
.element-related,
.browser-support {
    margin-bottom: var(--spacing-lg);
}

.element-syntax h4,
.element-attributes h4,
.element-accessibility h4,
.element-compatibility h4,
.element-best-practices h4,
.element-related h4 {
    font-size: 1rem;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--text-light);
    margin-bottom: var(--spacing-xs);
}

.mini-title {
    font-weight: 700;
    margin-bottom: var(--spacing-xs);
}

.mini-description {
    font-size: 0.9375rem;
    color: var(--text-light);
}

/* ==========================================================================
   Template previews
   ========================================================================== */

.template-preview {
    margin-bottom: var(--spacing-lg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    overflow: hidden;
    background-color: var(--background-alt);
}

.template-preview img {
    width: 100%;
    height: auto;
}

/* ==========================================================================
   Responsive
   ========================================================================== */

@media (max-width: 1024px) {
    .content-grid,
    .content-wrapper {
        grid-template-columns: minmax(0, 1fr);
    }

    .sidebar {
        position: static;
        grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    }
}

@media (max-width: 768px) {
    .main-nav {
        justify-content: flex-start;
    }

    .table-of-contents ul {
        columns: 1;
    }

    .content {
        padding: var(--spacing-xl) 0;
    }

    .cta-box,
    .submit-cta,
    .practice-section {
        padding: var(--spacing-lg);
    }
}

/* ==========================================================================
   Motion, dark mode, print
   ========================================================================== */

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }

    .example-card:hover,
    .category-card a:hover {
        transform: none;
    }
}

@media (prefers-color-scheme: dark) {
    :root {
        --primary-color: #60a5fa;
        --secondary-color: #93c5fd;
        --text-color: #e5e7eb;
        --text-light: #9ca3af;
        --background-color: #111827;
        --background-alt: #1f2937;
        --border-color: #374151;
        --code-background: #0b1120;
        --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.4);
        --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.5);
        --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.6);
    }

    footer {
        background-color: #0b1120;
    }

    .btn.primary {
        color: #0b1120;
    }

    .beginner     { background-color: rgba(16, 185, 129, 0.2); color: #6ee7b7; }
    .intermediate { background-color: rgba(245, 158, 11, 0.2); color: #fcd34d; }
    .advanced     { background-color: rgba(239, 68, 68, 0.2);  color: #fca5a5; }

    /* The live preview renders visitor markup that assumes a white page. */
    .preview,
    .preview iframe,
    .template-preview img {
        background-color: #fff;
    }
}

@media print {
    header, footer, .sidebar, .skip-link, .editor-controls,
    .device-selector, .cta-box, .submit-cta, .breadcrumbs {
        display: none !important;
    }

    .content-grid,
    .content-wrapper {
        grid-template-columns: 1fr;
    }

    body {
        color: #000;
        background: #fff;
    }

    .code-block,
    .code-example > pre {
        background: #f4f4f4;
        color: #000;
        border: 1px solid #ccc;
    }

    a[href^="http"]::after {
        content: " (" attr(href) ")";
        font-size: 0.85em;
        word-break: break-all;
    }
}

/* ==========================================================================
   Overflow containment & copy-button variants
   ========================================================================== */

/* Grid and flex children default to min-width:auto, which lets a wide <pre>
   push the whole column past the viewport. */
.sidebar,
.sidebar-widget,
.code-snippet,
.mini-example,
.footer-column {
    min-width: 0;
}

.sidebar pre,
.sidebar-widget pre,
.code-snippet pre {
    overflow-x: auto;
    max-width: 100%;
}

.code-snippet > pre {
    background-color: var(--code-background);
    color: var(--code-text);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    font-size: 0.8125rem;
}

.code-snippet h4 {
    font-size: 0.9375rem;
    margin-bottom: var(--spacing-xs);
}

/* All three copy-button class names get the same treatment. */
.copy-btn,
.copy-snippet {
    background-color: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-light);
    padding: 2px 10px;
    font-size: 0.8rem;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.copy-btn:hover,
.copy-snippet:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.copy-btn.is-error,
.copy-snippet.is-error {
    border-color: var(--error-color);
    color: var(--error-color);
}

.code-snippet {
    position: relative;
    margin-bottom: var(--spacing-md);
}

/* Nothing on the page may cause a horizontal scrollbar on the body. */
body {
    overflow-x: hidden;
}

.main-content pre,
.main-article pre,
.main-content table,
.main-article table {
    max-width: 100%;
}