/* LNG.org - Optimized CSS for PageSpeed 100/100 */
/* Critical path rendering optimized, minimal file size */

/* CSS Variables for performance */
:root {
    --color-primary: #0066cc;
    --color-primary-dark: #003d5c;
    --color-secondary: #00ccff;
    --color-text: #1a1a1a;
    --color-text-light: #4a4a4a;
    --color-bg: #ffffff;
    --color-bg-alt: #f5f7fa;
    --color-border: #e0e0e0;
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --font-mono: "SF Mono", Monaco, Consolas, monospace;
    --max-width: 1200px;
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --radius: 8px;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 20px rgba(0,0,0,0.15);
}

/* Base Reset & Typography */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
    font-family: var(--font-sans);
    color: var(--color-text);
    background: var(--color-bg);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Typography Scale */
h1 { font-size: clamp(2rem, 5vw, 3rem); font-weight: 700; line-height: 1.2; margin-bottom: var(--spacing-md); color: var(--color-primary-dark); }
h2 { font-size: clamp(1.5rem, 4vw, 2rem); font-weight: 600; line-height: 1.3; margin: var(--spacing-lg) 0 var(--spacing-md); color: var(--color-primary-dark); }
h3 { font-size: clamp(1.25rem, 3vw, 1.5rem); font-weight: 600; line-height: 1.4; margin: var(--spacing-md) 0 var(--spacing-sm); }
h4 { font-size: 1.125rem; font-weight: 600; line-height: 1.4; margin: var(--spacing-md) 0 var(--spacing-sm); }
p { margin-bottom: var(--spacing-sm); max-width: 75ch; }
.lead { font-size: 1.25rem; font-weight: 400; color: var(--color-text-light); line-height: 1.7; margin-bottom: var(--spacing-lg); }

a { color: var(--color-primary); text-decoration: none; transition: color 0.2s ease; }
a:hover { color: var(--color-primary-dark); text-decoration: underline; }

/* Container & Layout */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-lg) !important;
    width: 100%;
}
@media (min-width: 768px) {
    .container {
        padding: 0 var(--spacing-xl) !important;
    }
}
@media (min-width: 1024px) {
    .container {
        padding: 0 calc(var(--spacing-xl) * 1.5) !important;
    }
}

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

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

@media (min-width: 768px) {
    .nav-container {
        padding: var(--spacing-sm) var(--spacing-xl) !important;
    }
}

@media (min-width: 1024px) {
    .nav-container {
        padding: var(--spacing-sm) calc(var(--spacing-xl) * 1.5) !important;
    }
}

.logo a {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--color-primary-dark);
}

.logo a:hover { text-decoration: none; }

.nav-menu {
    display: none;
    list-style: none;
    gap: var(--spacing-lg);
    flex-direction: column;
}

@media (min-width: 768px) {
    .nav-menu {
        display: flex !important;
        flex-direction: row !important;
        align-items: center !important;
        gap: var(--spacing-lg) !important;
    }
}

.nav-menu a {
    font-weight: 500;
    color: var(--color-text);
    padding: 0.5rem 0;
    border-bottom: 2px solid transparent;
    transition: all 0.2s ease;
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--color-primary);
    border-bottom-color: var(--color-primary);
    text-decoration: none;
}

.mobile-toggle {
    display: block;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

@media (min-width: 768px) {
    .mobile-toggle { display: none; }
}

.mobile-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--color-text);
    margin: 5px 0;
    transition: 0.3s;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #003d5c 0%, #0066cc 100%);
    color: white;
    padding: var(--spacing-xl) 0;
    text-align: center;
}

.hero-content {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg) !important;
}
@media (min-width: 768px) {
    .hero-content {
        padding: 0 var(--spacing-xl) !important;
    }
}
@media (min-width: 1024px) {
    .hero-content {
        padding: 0 calc(var(--spacing-xl) * 1.5) !important;
    }
}
.hero h1 { color: white; margin-bottom: var(--spacing-md); }
.hero-subtitle { font-size: 1.125rem; opacity: 0.9; margin-bottom: var(--spacing-lg); }

.hero-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-md);
    margin: var(--spacing-xl) 0;
}

.stat-card {
    background: rgba(255, 255, 255, 0.1);
    padding: var(--spacing-md);
    border-radius: var(--radius);
    backdrop-filter: blur(10px);
}

.stat-value {
    display: block;
    font-size: 2rem;
    font-weight: 700;
    color: var(--color-secondary);
}

.stat-label {
    display: block;
    font-size: 0.875rem;
    opacity: 0.9;
    margin-top: var(--spacing-xs);
}

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

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius);
    font-weight: 600;
    transition: all 0.2s ease;
    border: 2px solid transparent;
}

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

.btn-primary:hover {
    background: white;
    text-decoration: none;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: transparent;
    border-color: white;
    color: white;
}

.btn-secondary:hover {
    background: white;
    color: var(--color-primary);
    text-decoration: none;
    transform: translateY(-2px);
}

/* Sections */
section { padding: var(--spacing-xl) 0; }
.intro-section { background: var(--color-bg-alt); }

.feature-grid,
.knowledge-grid,
.facts-grid {
    display: grid;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

.feature-grid { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.knowledge-grid { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }

.feature-card,
.knowledge-card,
.trade-card {
    background: white;
    padding: var(--spacing-lg);
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
}

.feature-card:hover,
.knowledge-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

.knowledge-card {
    display: flex;
    flex-direction: column;
    color: var(--color-text);
}

.knowledge-card:hover { text-decoration: none; }

.knowledge-card h3 { color: var(--color-primary-dark); margin-bottom: var(--spacing-sm); }
.knowledge-card p { flex-grow: 1; color: var(--color-text-light); }

.read-time {
    display: inline-block;
    margin-top: var(--spacing-sm);
    font-size: 0.875rem;
    color: var(--color-primary);
    font-weight: 600;
}

.feature-icon { margin-bottom: var(--spacing-md); }

.card-link {
    display: inline-block;
    margin-top: var(--spacing-sm);
    color: var(--color-primary);
    font-weight: 600;
}

/* Key Facts Grid */
.facts-grid {
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-md);
}

.fact-item {
    text-align: center;
    padding: var(--spacing-md);
    background: white;
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
}

.fact-item strong {
    display: block;
    font-size: 1.75rem;
    color: var(--color-primary);
    margin-bottom: var(--spacing-xs);
}

.fact-item span {
    display: block;
    font-size: 0.875rem;
    color: var(--color-text-light);
}

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

table {
    width: 100%;
    border-collapse: collapse;
    background: white;
    box-shadow: var(--shadow-sm);
    border-radius: var(--radius);
    overflow: hidden;
}

caption {
    caption-side: top;
    text-align: left;
    font-weight: 600;
    padding: var(--spacing-sm);
    background: var(--color-bg-alt);
}

thead {
    background: var(--color-primary-dark);
    color: white;
}

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

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

.comparison-table th:first-child,
.comparison-table td:first-child {
    font-weight: 600;
}

.comparison-note {
    margin-top: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--color-bg-alt);
    border-left: 4px solid var(--color-primary);
    border-radius: var(--radius);
}

/* Trade Cards */
.trade-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin: var(--spacing-lg) 0;
}

.export-list,
.import-list {
    list-style: none;
    counter-reset: item;
}

.export-list li,
.import-list li {
    counter-increment: item;
    margin-bottom: var(--spacing-sm);
    padding-left: 2rem;
    position: relative;
}

.export-list li::before,
.import-list li::before {
    content: counter(item);
    position: absolute;
    left: 0;
    top: 0;
    background: var(--color-primary);
    color: white;
    width: 1.5rem;
    height: 1.5rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.875rem;
}

/* Highlight Boxes */
.highlight-box,
.info-box {
    margin: var(--spacing-lg) 0;
    padding: var(--spacing-lg);
    border-radius: var(--radius);
    border-left: 4px solid var(--color-primary);
}

.highlight-box {
    background: #e6f2ff;
}

.info-box {
    background: var(--color-bg-alt);
}

.highlight-box h3,
.info-box h3 {
    margin-top: 0;
    color: var(--color-primary-dark);
}

/* Article Content */
.content-article {
    max-width: 900px;
    margin: 0 auto;
    padding: var(--spacing-lg) var(--spacing-lg) !important;
}
@media (min-width: 768px) {
    .content-article {
        padding: var(--spacing-xl) var(--spacing-xl) !important;
    }
}
@media (min-width: 1024px) {
    .content-article {
        padding: var(--spacing-xl) calc(var(--spacing-xl) * 1.5) !important;
    }
}

.breadcrumb {
    font-size: 0.875rem;
    color: var(--color-text-light);
    margin-bottom: var(--spacing-md);
}

.breadcrumb a { color: var(--color-primary); }

.article-header {
    margin-bottom: var(--spacing-xl);
    border-bottom: 2px solid var(--color-border);
    padding-bottom: var(--spacing-md);
}

.article-meta {
    font-size: 0.875rem;
    color: var(--color-text-light);
    margin-top: var(--spacing-sm);
}

.article-content { font-size: 1.0625rem; line-height: 1.7; }
.article-content ul, .article-content ol { margin: var(--spacing-md) 0; padding-left: 1.5rem; }
.article-content li { margin-bottom: var(--spacing-xs); }

.intro-block {
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-lg);
    background: var(--color-bg-alt);
    border-radius: var(--radius);
}

.key-points {
    list-style: none;
    padding: 0;
}

.key-points li {
    padding-left: 2rem;
    position: relative;
    margin-bottom: var(--spacing-sm);
}

.key-points li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--color-primary);
    font-weight: 700;
    font-size: 1.25rem;
}

.related-topics {
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-xl);
    border-top: 2px solid var(--color-border);
}

.related-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.related-card {
    padding: var(--spacing-md);
    background: var(--color-bg-alt);
    border-radius: var(--radius);
    border-left: 4px solid var(--color-primary);
    transition: all 0.2s ease;
    color: var(--color-text);
}

.related-card:hover {
    background: white;
    box-shadow: var(--shadow-md);
    text-decoration: none;
    transform: translateX(4px);
}

.related-card h3 { color: var(--color-primary); margin-bottom: var(--spacing-xs); font-size: 1.125rem; }
.related-card p { color: var(--color-text-light); font-size: 0.9375rem; }

/* Glossary Specific */
.glossary-nav {
    position: sticky;
    top: 70px;
    background: var(--color-bg);
    padding: var(--spacing-md) 0;
    border-bottom: 1px solid var(--color-border);
    margin-bottom: var(--spacing-lg);
    text-align: center;
    z-index: 50;
}

.glossary-nav a {
    display: inline-block;
    padding: 0.25rem 0.5rem;
    margin: 0.125rem;
    font-weight: 600;
    font-size: 0.875rem;
}

.glossary-section { margin-bottom: var(--spacing-xl); }
.glossary-section h2 {
    font-size: 2rem;
    color: var(--color-primary);
    padding-bottom: var(--spacing-sm);
    border-bottom: 3px solid var(--color-primary);
    margin-bottom: var(--spacing-md);
}

.glossary-list dt {
    font-size: 1.125rem;
    margin-top: var(--spacing-md);
    color: var(--color-primary-dark);
}

.glossary-list dd {
    margin: var(--spacing-xs) 0 var(--spacing-md) var(--spacing-md);
    color: var(--color-text-light);
    line-height: 1.7;
}

/* Footer */
.site-footer {
    background: var(--color-primary-dark);
    color: white;
    padding: var(--spacing-xl) 0 var(--spacing-md);
    margin-top: var(--spacing-xl);
}

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

.footer-col h4 {
    color: var(--color-secondary);
    margin-bottom: var(--spacing-sm);
    font-size: 1rem;
}

.footer-col p { font-size: 0.9375rem; opacity: 0.9; }

.footer-col ul { list-style: none; }
.footer-col li { margin-bottom: var(--spacing-xs); }
.footer-col a { color: white; opacity: 0.9; }
.footer-col a:hover { opacity: 1; color: var(--color-secondary); }

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-md);
    border-top: 1px solid rgba(255, 255, 255, 0.2);
    font-size: 0.875rem;
    opacity: 0.8;
}

/* Responsive Utilities */
@media (max-width: 767px) {
    .hero-stats { grid-template-columns: repeat(2, 1fr); }
    .stat-value { font-size: 1.5rem; }
    .facts-grid { grid-template-columns: 1fr; }
    table { font-size: 0.875rem; }
    th, td { padding: 0.5rem; }
}

/* Print Styles */
@media print {
    .site-header, .site-footer, .cta-buttons, .related-topics, .glossary-nav { display: none; }
    body { font-size: 12pt; line-height: 1.5; }
    h1 { font-size: 20pt; }
    h2 { font-size: 16pt; }
    a { color: #000; text-decoration: underline; }
}

/* Performance: Reduce animations for users who prefer reduced motion */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* Focus styles for accessibility */
*:focus-visible {
    outline: 3px solid var(--color-secondary);
    outline-offset: 2px;
}

/* Skip to main content link for accessibility */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--color-primary);
    color: white;
    padding: var(--spacing-sm);
    z-index: 1000;
}

.skip-link:focus { top: 0; }

/* Lazy load images placeholder */
img { max-width: 100%; height: auto; }
img[loading="lazy"] { background: var(--color-bg-alt); }