/* ==========================================================================
   OverviewBrief - Main Stylesheet
   Premium AI Publication Design
   ========================================================================== */

/* Custom Properties */
:root {
    --color-bg: #01030A;
    --color-text: #FDFDFD;
    --color-accent: #3380F7;
    --color-accent-light: #60A0FB;
    --color-highlight: #CDDCF2;
    --color-gray-900: #0a0e17;
    --color-gray-800: #111827;
    --color-gray-700: #1f2937;
    --color-gray-600: #374151;
    --color-gray-500: #6b7280;
    --color-gray-400: #9ca3af;
    --color-gray-300: #d1d5db;
    
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'SF Mono', 'Fira Code', 'Fira Mono', 'Roboto Mono', monospace;
    
    --max-width: 1200px;
    --nav-height: 72px;
    
    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 20px;
}

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

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

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

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

a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color 0.2s ease;
}

a:hover {
    color: var(--color-accent-light);
}

/* Skip Link */
.skip-link {
    position: absolute;
    top: -100%;
    left: 16px;
    background: var(--color-accent);
    color: var(--color-text);
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    z-index: 1000;
    font-weight: 600;
}

.skip-link:focus {
    top: 16px;
}

/* Container */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* Navigation */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: rgba(1, 3, 10, 0.92);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-gray-800);
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--nav-height);
}

.logo-link {
    display: flex;
    align-items: center;
    flex-shrink: 0;
}

.logo {
    height: 32px;
    width: auto;
}

.nav-list {
    display: flex;
    list-style: none;
    gap: 8px;
}

.nav-link {
    color: var(--color-gray-400);
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    font-size: 0.9375rem;
    font-weight: 500;
    transition: color 0.2s ease, background-color 0.2s ease;
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-text);
    background-color: var(--color-gray-800);
}

.social-links {
    display: flex;
    gap: 8px;
    align-items: center;
}

.social-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: var(--radius-sm);
    color: var(--color-gray-400);
    transition: color 0.2s ease, background-color 0.2s ease;
}

.social-link:hover {
    color: var(--color-text);
    background-color: var(--color-gray-800);
}

.social-icon {
    width: 18px;
    height: 18px;
}

/* Mobile Nav Toggle */
.mobile-nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
    z-index: 101;
}

.hamburger-line {
    display: block;
    width: 24px;
    height: 2px;
    background-color: var(--color-text);
    transition: transform 0.3s ease, opacity 0.3s ease;
}

.mobile-nav-toggle[aria-expanded="true"] .hamburger-line:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.mobile-nav-toggle[aria-expanded="true"] .hamburger-line:nth-child(2) {
    opacity: 0;
}

.mobile-nav-toggle[aria-expanded="true"] .hamburger-line:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* Sections */
.section {
    padding: 80px 0;
}

.section-header {
    margin-bottom: 48px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 16px;
}

.section-title,
.section-header h2 {
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.section-subtitle {
    color: var(--color-gray-400);
    font-size: 1.125rem;
    margin-top: 8px;
}

.view-all {
    font-size: 0.9375rem;
    font-weight: 500;
}

/* Hero */
.hero {
    padding: 120px 0 100px;
    text-align: center;
}

.hero-container {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 24px;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.1;
    letter-spacing: -0.03em;
    margin-bottom: 24px;
    color: var(--color-text);
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--color-gray-400);
    margin-bottom: 40px;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-cta {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 28px;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 600;
    border: 2px solid transparent;
    cursor: pointer;
    transition: all 0.2s ease;
    text-decoration: none;
}

.btn-primary {
    background-color: var(--color-accent);
    color: var(--color-text);
    border-color: var(--color-accent);
}

.btn-primary:hover {
    background-color: var(--color-accent-light);
    border-color: var(--color-accent-light);
    color: var(--color-text);
}

.btn-secondary {
    background-color: transparent;
    color: var(--color-text);
    border-color: var(--color-gray-600);
}

.btn-secondary:hover {
    border-color: var(--color-gray-400);
    color: var(--color-text);
}

.btn-outline {
    background-color: transparent;
    color: var(--color-text);
    border-color: var(--color-gray-600);
}

.btn-outline:hover {
    border-color: var(--color-accent);
    color: var(--color-accent);
}

.center-cta {
    text-align: center;
    margin-top: 48px;
}

/* News Preview Grid */
.news-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 32px;
}

.news-card {
    background-color: var(--color-gray-900);
    border: 1px solid var(--color-gray-800);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: border-color 0.2s ease, transform 0.2s ease;
}

.news-card:hover {
    border-color: var(--color-gray-700);
    transform: translateY(-2px);
}

.news-card-embed {
    background-color: var(--color-gray-800);
    min-height: 400px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.embed-placeholder {
    color: var(--color-gray-500);
    font-size: 0.875rem;
    text-align: center;
    padding: 24px;
}

.news-card-meta {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 20px 20px 0;
}

.category-tag {
    display: inline-block;
    padding: 4px 12px;
    background-color: rgba(51, 128, 247, 0.15);
    color: var(--color-accent-light);
    border-radius: 100px;
    font-size: 0.8125rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.03em;
}

.news-card-meta time {
    color: var(--color-gray-500);
    font-size: 0.875rem;
}

.news-card-title {
    padding: 12px 20px 24px;
    font-size: 1.125rem;
    font-weight: 600;
}

/* Concept Cards */
.concept-cards {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 24px;
}

.concept-card {
    background-color: var(--color-gray-900);
    border: 1px solid var(--color-gray-800);
    border-radius: var(--radius-lg);
    padding: 28px;
    display: flex;
    flex-direction: column;
    gap: 16px;
    transition: border-color 0.2s ease, transform 0.2s ease;
    text-decoration: none;
    color: var(--color-text);
}

.concept-card:hover {
    border-color: var(--color-accent);
    transform: translateY(-2px);
    color: var(--color-text);
}

.concept-card h3 {
    font-size: 1.25rem;
    font-weight: 700;
}

.concept-card p {
    color: var(--color-gray-400);
    font-size: 0.9375rem;
    line-height: 1.7;
    flex-grow: 1;
}

.learn-more {
    color: var(--color-accent);
    font-size: 0.9375rem;
    font-weight: 600;
}

.concept-card:hover .learn-more {
    color: var(--color-accent-light);
}

/* Topics */
.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 16px;
}

.topic-card {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 24px;
    background-color: var(--color-gray-900);
    border: 1px solid var(--color-gray-800);
    border-radius: var(--radius-md);
    color: var(--color-gray-300);
    font-weight: 500;
    font-size: 0.9375rem;
    text-align: center;
    transition: all 0.2s ease;
    text-decoration: none;
}

.topic-card:hover {
    border-color: var(--color-accent);
    color: var(--color-text);
    background-color: rgba(51, 128, 247, 0.05);
}

/* Social CTA */
.social-cta {
    text-align: center;
    background-color: var(--color-gray-900);
    border: 1px solid var(--color-gray-800);
    border-radius: var(--radius-lg);
    margin: 0 24px;
    padding: 64px 24px;
}

.social-cta .container {
    max-width: 600px;
}

.social-cta h2 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 16px;
}

.social-cta p {
    color: var(--color-gray-400);
    margin-bottom: 32px;
    font-size: 1.0625rem;
}

.social-cta-links {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

/* Footer */
.site-footer {
    border-top: 1px solid var(--color-gray-800);
    padding: 64px 0 32px;
    margin-top: 80px;
}

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

.footer-brand {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.footer-logo {
    height: 28px;
    width: auto;
}

.footer-tagline {
    color: var(--color-gray-500);
    font-size: 0.8125rem;
    letter-spacing: 0.05em;
}

.footer-links {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

.footer-column h4 {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-gray-400);
    margin-bottom: 16px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.footer-column ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.footer-column a {
    color: var(--color-gray-500);
    font-size: 0.9375rem;
    transition: color 0.2s ease;
}

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

.footer-bottom {
    border-top: 1px solid var(--color-gray-800);
    padding-top: 24px;
    text-align: center;
}

.footer-bottom p {
    color: var(--color-gray-500);
    font-size: 0.875rem;
}

.footer-bottom a {
    color: var(--color-gray-400);
}

.footer-bottom a:hover {
    color: var(--color-text);
}

/* Breadcrumbs */
.breadcrumbs {
    padding: 24px 0;
    font-size: 0.875rem;
    color: var(--color-gray-500);
}

.breadcrumbs ol {
    list-style: none;
    display: flex;
    gap: 8px;
    align-items: center;
    flex-wrap: wrap;
}

.breadcrumbs li {
    display: flex;
    align-items: center;
    gap: 8px;
}

.breadcrumbs li:not(:last-child)::after {
    content: '→';
    color: var(--color-gray-600);
}

.breadcrumbs a {
    color: var(--color-gray-400);
}

.breadcrumbs a:hover {
    color: var(--color-text);
}

/* Learn Page */
.learn-header {
    padding: 80px 0 48px;
    text-align: center;
}

.learn-header h1 {
    font-size: 3rem;
    font-weight: 800;
    letter-spacing: -0.03em;
    margin-bottom: 16px;
}

.learn-header p {
    color: var(--color-gray-400);
    font-size: 1.125rem;
    max-width: 600px;
    margin: 0 auto;
}

.filter-bar {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    margin-bottom: 48px;
    justify-content: center;
}

.filter-btn {
    padding: 8px 20px;
    border: 1px solid var(--color-gray-700);
    background: none;
    color: var(--color-gray-400);
    border-radius: 100px;
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.filter-btn:hover {
    border-color: var(--color-gray-500);
    color: var(--color-text);
}

.filter-btn.active {
    background-color: var(--color-accent);
    border-color: var(--color-accent);
    color: var(--color-text);
}

.concept-library {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 24px;
}

/* Concept Page */
.concept-article {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 24px 80px;
}

.concept-header {
    margin-bottom: 40px;
}

.concept-header .category-tag {
    margin-bottom: 16px;
}

.concept-header h1 {
    font-size: 2.5rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    line-height: 1.2;
    margin-bottom: 24px;
}

.short-answer {
    background-color: var(--color-gray-900);
    border: 1px solid var(--color-gray-800);
    border-left: 4px solid var(--color-accent);
    border-radius: var(--radius-md);
    padding: 24px;
    margin-bottom: 40px;
}

.short-answer h2 {
    font-size: 1rem;
    color: var(--color-accent-light);
    margin-bottom: 8px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.short-answer p {
    font-size: 1.125rem;
    line-height: 1.8;
    color: var(--color-gray-200);
}

.concept-content h2 {
    font-size: 1.75rem;
    font-weight: 700;
    margin: 40px 0 16px;
    color: var(--color-text);
}

.concept-content h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin: 32px 0 12px;
    color: var(--color-gray-200);
}

.concept-content p {
    font-size: 1.0625rem;
    line-height: 1.8;
    color: var(--color-gray-300);
    margin-bottom: 16px;
}

.concept-content ul,
.concept-content ol {
    margin: 16px 0;
    padding-left: 24px;
    color: var(--color-gray-300);
}

.concept-content li {
    margin-bottom: 8px;
    line-height: 1.7;
}

.simple-explanation {
    background-color: rgba(51, 128, 247, 0.05);
    border: 1px solid rgba(51, 128, 247, 0.2);
    border-radius: var(--radius-lg);
    padding: 28px;
    margin: 40px 0;
}

.simple-explanation h2 {
    color: var(--color-accent-light);
    font-size: 1.25rem;
    margin-top: 0;
}

.simple-explanation p {
    color: var(--color-gray-200);
}

.analogy-box {
    background-color: var(--color-gray-900);
    border: 1px solid var(--color-gray-700);
    border-radius: var(--radius-lg);
    padding: 28px;
    margin: 40px 0;
}

.analogy-box h3 {
    color: var(--color-highlight);
    font-size: 1.125rem;
    margin-top: 0;
}

.faq-section {
    margin: 48px 0;
}

.faq-section h2 {
    margin-bottom: 24px;
}

.faq-item {
    border-bottom: 1px solid var(--color-gray-800);
    padding: 20px 0;
}

.faq-item:first-child {
    border-top: 1px solid var(--color-gray-800);
}

.faq-item h3 {
    font-size: 1.125rem;
    margin: 0 0 8px;
}

.faq-item p {
    margin: 0;
}

.related-concepts {
    margin: 48px 0;
    padding: 32px;
    background-color: var(--color-gray-900);
    border-radius: var(--radius-lg);
}

.related-concepts h2 {
    margin-top: 0;
    margin-bottom: 20px;
}

.related-links {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

.related-link {
    display: inline-block;
    padding: 10px 20px;
    background-color: var(--color-gray-800);
    border-radius: var(--radius-md);
    color: var(--color-gray-300);
    font-size: 0.9375rem;
    transition: all 0.2s ease;
}

.related-link:hover {
    background-color: var(--color-accent);
    color: var(--color-text);
}

.concept-cta {
    text-align: center;
    margin-top: 48px;
    padding: 40px;
    background-color: var(--color-gray-900);
    border-radius: var(--radius-lg);
}

.concept-cta p {
    color: var(--color-gray-400);
    margin-bottom: 20px;
}

/* About Page */
.about-header {
    padding: 80px 0 48px;
    text-align: center;
}

.about-header h1 {
    font-size: 3rem;
    font-weight: 800;
    letter-spacing: -0.03em;
}

.about-content {
    max-width: 720px;
    margin: 0 auto;
    padding: 0 24px 80px;
}

.about-content h2 {
    font-size: 1.75rem;
    font-weight: 700;
    margin: 48px 0 16px;
}

.about-content p {
    font-size: 1.0625rem;
    line-height: 1.8;
    color: var(--color-gray-300);
    margin-bottom: 16px;
}

.about-pillars {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
    margin: 32px 0;
}

.pillar-card {
    background-color: var(--color-gray-900);
    border: 1px solid var(--color-gray-800);
    border-radius: var(--radius-lg);
    padding: 28px;
}

.pillar-card h3 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--color-accent-light);
}

.pillar-card p {
    font-size: 0.9375rem;
    margin: 0;
}

.axinity-section {
    margin-top: 48px;
    padding: 32px;
    background-color: var(--color-gray-900);
    border: 1px solid var(--color-gray-800);
    border-radius: var(--radius-lg);
    text-align: center;
}

.axinity-section h2 {
    margin-top: 0;
}

/* Privacy Page */
.privacy-content {
    max-width: 720px;
    margin: 0 auto;
    padding: 0 24px 80px;
}

.privacy-content h1 {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 8px;
}

.last-updated {
    color: var(--color-gray-500);
    font-size: 0.875rem;
    margin-bottom: 40px;
}

.privacy-content h2 {
    font-size: 1.5rem;
    font-weight: 700;
    margin: 40px 0 16px;
}

.privacy-content p {
    font-size: 1rem;
    line-height: 1.8;
    color: var(--color-gray-300);
    margin-bottom: 16px;
}

.privacy-content ul {
    margin: 16px 0;
    padding-left: 24px;
    color: var(--color-gray-300);
}

.privacy-content li {
    margin-bottom: 8px;
}

/* 404 Page */
.error-page {
    min-height: calc(100vh - var(--nav-height) - 200px);
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 80px 24px;
}

.error-content {
    max-width: 500px;
}

.error-code {
    font-size: 6rem;
    font-weight: 800;
    color: var(--color-accent);
    line-height: 1;
    margin-bottom: 16px;
}

.error-content h1 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 16px;
}

.error-content p {
    color: var(--color-gray-400);
    margin-bottom: 32px;
    font-size: 1.0625rem;
}

.error-cta {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

/* News Page */
.news-header {
    padding: 80px 0 48px;
    text-align: center;
}

.news-header h1 {
    font-size: 3rem;
    font-weight: 800;
    letter-spacing: -0.03em;
    margin-bottom: 16px;
}

.news-header p {
    color: var(--color-gray-400);
    font-size: 1.125rem;
    max-width: 600px;
    margin: 0 auto;
}

.news-feed {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 24px 80px;
}

.news-item {
    background-color: var(--color-gray-900);
    border: 1px solid var(--color-gray-800);
    border-radius: var(--radius-lg);
    overflow: hidden;
    margin-bottom: 32px;
}

.news-item-meta {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 24px 24px 0;
}

.news-item-meta time {
    color: var(--color-gray-500);
    font-size: 0.875rem;
}

.news-item-title {
    padding: 12px 24px;
    font-size: 1.25rem;
    font-weight: 600;
}

.news-item-description {
    padding: 0 24px 12px;
    color: var(--color-gray-400);
    font-size: 0.9375rem;
    line-height: 1.7;
}

.instagram-embed {
    background-color: var(--color-gray-800);
    min-height: 500px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-gray-500);
    font-size: 0.875rem;
}

/* Responsive Design */
@media (max-width: 820px) {
    .mobile-nav-toggle {
        display: flex;
    }

    .nav-list {
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background-color: rgba(1, 3, 10, 0.98);
        backdrop-filter: blur(16px);
        -webkit-backdrop-filter: blur(16px);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 28px;
        padding: 40px 24px;
        transform: translateX(100%);
        transition: transform 0.35s cubic-bezier(0.4, 0, 0.2, 1);
        z-index: 101;
        overflow-y: auto;
    }

    /* The class that JS toggles to open the menu */
    .nav-list.is-open {
        transform: translateX(0);
    }

    .nav-link {
        font-size: 1.5rem;
        padding: 10px 24px;
        white-space: normal;
        text-align: center;
        width: 100%;
        max-width: 280px;
    }

    /* Hide desktop social icons, show them inside the overlay instead */
    .social-links {
        display: none;
    }

    /* Mobile social row (inside the overlay) */
    .nav-list .mobile-social-row {
        display: flex;
        gap: 16px;
        margin-top: 16px;
        justify-content: center;
        list-style: none;
    }

    .nav-list .mobile-social-row .social-link {
        width: 44px;
        height: 44px;
        background-color: var(--color-gray-800);
        border-radius: 50%;
        color: var(--color-gray-400);
        display: flex;
        align-items: center;
        justify-content: center;
    }

    .nav-list .mobile-social-row .social-link:hover {
        background-color: var(--color-gray-700);
        color: var(--color-text);
    }
}
    
    .hero-title {
        font-size: 2.25rem;
    }
    
    .hero-subtitle {
        font-size: 1.0625rem;
    }
    
    .section {
        padding: 48px 0;
    }
    
    .section-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .section-title,
    .section-header h2 {
        font-size: 1.5rem;
    }
    
    .concept-cards,
    .news-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    .footer-links {
        grid-template-columns: 1fr;
    }
    
    .concept-header h1 {
        font-size: 1.75rem;
    }
    
    .learn-header h1,
    .news-header h1,
    .about-header h1 {
        font-size: 2rem;
    }
    
    .error-code {
        font-size: 4rem;
    }
    
    .social-cta {
        margin: 0 16px;
        padding: 48px 16px;
    }

@media (min-width: 769px) and (max-width: 1024px) {
    .hero-title {
        font-size: 2.75rem;
    }
    
    .concept-cards,
    .news-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* Focus States */
:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

/* Utility */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border-width: 0;
}

body.nav-open {
    overflow: hidden;
}

.btn,
.topic-card,
.concept-card,
.nav-link,
.social-link,
.mobile-nav-toggle {
    -webkit-tap-highlight-color: transparent;
}