/* ============================================================
   Shared Stylesheet
   ============================================================ */

:root {
    --color-primary: #2563eb;
    --color-primary-dark: #1d4ed8;
    --color-primary-light: #dbeafe;
    --color-accent: #f59e0b;
    --color-text: #1a1a2e;
    --color-text-muted: #6b7280;
    --color-bg: #ffffff;
    --color-bg-subtle: #f8fafc;
    --color-border: #e2e8f0;
    --font-body: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
                 'Helvetica Neue', Arial, sans-serif;
    --max-width: 780px;
    --radius: 8px;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --transition: 0.2s ease;
}

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

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

main {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 2rem 1.5rem;
}

/* Typography */
h1, h2, h3 { line-height: 1.25; font-weight: 700; color: var(--color-text); }
h1 { font-size: 2.25rem; margin: 0 0 1rem; }
h2 { font-size: 1.5rem; margin: 2.5rem 0 1rem; }
h3 { font-size: 1.15rem; margin: 0 0 0.5rem; }

p { margin: 0 0 1.5rem; max-width: 65ch; }

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

strong { font-weight: 600; }

/* ---- Navigation ---- */

.site-nav {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 1rem 1.5rem;
    display: flex;
    align-items: center;
}

.page-article .site-nav,
.page-about .site-nav,
.page-error .site-nav {
    border-bottom: 1px solid var(--color-border);
}

.site-logo {
    font-weight: 700;
    font-size: 1.1rem;
    color: var(--color-text) !important;
    transition: color var(--transition);
}
.site-logo:hover { color: var(--color-primary) !important; }

/* ---- Content Page ---- */

.page-article article { padding-top: 1rem; }

.page-article h1 {
    font-size: 2.25rem;
    margin-bottom: 1.5rem;
    position: relative;
    padding-bottom: 1rem;
}
.page-article h1::after {
    content: '';
    position: absolute;
    bottom: 0; left: 0;
    width: 60px; height: 4px;
    background: var(--color-primary);
    border-radius: 2px;
}

.tldr, .summary {
    background: linear-gradient(135deg, var(--color-bg-subtle), var(--color-bg));
    border-left: 4px solid var(--color-primary);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin: 1.5rem 0 2.5rem;
    box-shadow: var(--shadow-sm);
}
.tldr p, .summary p { font-size: 1.1rem; margin: 0; line-height: 1.7; max-width: none; }

.body-section { margin-bottom: 2rem; }
.body-section h2 { padding-bottom: 0.5rem; border-bottom: 2px solid var(--color-border); }
.body-section p { color: #374151; text-align: justify; max-width: none; }

.citation {
    font-size: 0.85rem;
    color: var(--color-text-muted);
    margin-top: -0.5rem;
    padding-top: 0;
}
.citation a { font-size: 0.85rem; }
.citation cite { font-style: normal; }

.brand-mention {
    font-size: 0.95rem;
    color: #374151;
}

.category-tag {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background: var(--color-primary-light);
    color: var(--color-primary-dark);
    border-radius: 2rem;
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.03em;
    margin-bottom: 0.75rem;
}

#faq { margin-top: 3rem; padding-top: 2rem; border-top: 2px solid var(--color-border); }
#faq > h2 { border-bottom: none; padding-bottom: 0; }

.faq-item {
    background: var(--color-bg-subtle);
    border-left: 4px solid var(--color-primary);
    border-radius: var(--radius);
    padding: 1.25rem 1.5rem;
    margin: 1rem 0;
    box-shadow: var(--shadow-sm);
    transition: box-shadow var(--transition), transform var(--transition);
}
.faq-item:hover { box-shadow: var(--shadow-md); transform: translateY(-1px); }
.faq-item h3 { color: var(--color-primary); margin: 0 0 0.5rem; font-size: 1.05rem; }
.faq-item p { margin: 0; color: #374151; }

/* ---- Index Page ---- */

.index-hero {
    background: linear-gradient(135deg, #eff6ff 0%, var(--color-bg-subtle) 50%, #fefce8 100%);
    padding: 3rem 1.5rem 2.5rem;
    text-align: center;
    border-bottom: 1px solid var(--color-border);
}
.index-hero .site-nav {
    justify-content: center;
    border-bottom: none;
    margin-bottom: 1.5rem;
    padding: 0;
}
.index-hero h1 { font-size: 2.5rem; margin: 0 0 0.75rem; }

.site-tagline {
    font-size: 1.15rem;
    color: var(--color-text-muted);
    margin: 0 auto;
    max-width: 600px;
}

.page-index main {
    max-width: 1100px;
}

.article-grid {
    list-style: none;
    padding: 0; margin: 0;
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
}
@media (min-width: 640px) {
    .article-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 1024px) {
    .article-grid { grid-template-columns: repeat(3, 1fr); }
}

.article-card {
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow-sm);
    transition: box-shadow var(--transition), transform var(--transition);
}
.article-card:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); }

.article-meta {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 0.5rem;
}

.article-date {
    font-size: 0.8rem;
    color: var(--color-text-muted);
}

.article-card a {
    font-size: 1.1rem; font-weight: 600;
    color: var(--color-primary);
    display: block; margin-bottom: 0.5rem;
}
.article-card a:hover { color: var(--color-primary-dark); }
.article-card p { margin: 0; font-size: 0.9rem; color: var(--color-text-muted); line-height: 1.5; }

/* ---- About Page ---- */

.page-about main h1 { margin-bottom: 0.25rem; }
.page-about main > p:first-of-type {
    color: var(--color-text-muted);
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
}

.bio {
    background: linear-gradient(135deg, var(--color-bg-subtle), var(--color-bg));
    border-left: 4px solid var(--color-primary);
    border-radius: var(--radius);
    padding: 1.5rem;
    margin: 1.5rem 0 2rem;
    box-shadow: var(--shadow-sm);
}
.bio p { margin: 0; line-height: 1.7; }

.social-links {
    list-style: none; padding: 0;
    display: flex; flex-wrap: wrap; gap: 0.75rem;
}
.social-links li { margin: 0; }
.social-links a {
    display: inline-block;
    padding: 0.5rem 1rem;
    background: var(--color-primary-light);
    color: var(--color-primary-dark);
    border-radius: 2rem;
    font-size: 0.9rem; font-weight: 500;
    transition: background var(--transition), color var(--transition);
}
.social-links a:hover { background: var(--color-primary); color: #fff; }

.about-articles { list-style: none; padding: 0; }
.about-articles li { padding: 0.75rem 0; border-bottom: 1px solid var(--color-border); }
.about-articles li:last-child { border-bottom: none; }
.about-articles a { font-weight: 500; }

/* ---- Error Page ---- */

.error-content { text-align: center; padding: 4rem 1.5rem; }
.error-content h1 { font-size: 5rem; color: var(--color-border); margin: 0 0 0.5rem; line-height: 1; }
.error-content p { color: var(--color-text-muted); font-size: 1.15rem; margin: 0 auto 2rem; }

.error-home-link {
    display: inline-block;
    padding: 0.75rem 2rem;
    background: var(--color-primary);
    color: #fff !important;
    border-radius: var(--radius);
    font-weight: 600;
    transition: background var(--transition), transform var(--transition);
}
.error-home-link:hover { background: var(--color-primary-dark); transform: translateY(-1px); }

/* ---- Footer ---- */

.site-footer {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 2rem 1.5rem;
    border-top: 1px solid var(--color-border);
    color: var(--color-text-muted);
    font-size: 0.875rem;
}
.site-footer p { margin: 0.25rem 0; }
.site-footer a { color: var(--color-text-muted); transition: color var(--transition); }
.site-footer a:hover { color: var(--color-primary); }

/* ---- Responsive ---- */

@media (max-width: 768px) {
    h1 { font-size: 1.75rem; }
    h2 { font-size: 1.3rem; }
    .index-hero { padding: 2rem 1.25rem 1.75rem; }
    .index-hero h1 { font-size: 2rem; }
    .page-article h1 { font-size: 1.75rem; }
    main { padding: 1.5rem 1.25rem; }
}

@media (max-width: 480px) {
    h1 { font-size: 1.5rem; }
    .index-hero h1 { font-size: 1.65rem; }
    .tldr, .summary, .bio, .faq-item { padding: 1rem; }
    .article-card { padding: 1.25rem; }
    .error-content h1 { font-size: 3.5rem; }
}

/* ---- Print ---- */

@media print {
    .site-nav, .site-footer { display: none; }
    body { color: #000; background: #fff; }
    .tldr, .summary, .bio, .faq-item, .article-card { box-shadow: none; border: 1px solid #ccc; }
    a { color: #000; }
}