:root {
    --color-bg: #ffffff;
    --color-surface: #f6f8fa;
    --color-text: #1c2733;
    --color-muted: #5b6b7c;
    --color-primary: #1a6091;
    --color-primary-dark: #124a70;
    --color-border: #e2e8ef;
    --radius: 10px;
    --shadow: 0 4px 14px rgba(20, 30, 40, 0.06);
    --max-width: 1080px;
    --content-width: 720px;
}

@media (prefers-color-scheme: dark) {
    :root {
        --color-bg: #10151b;
        --color-surface: #171e26;
        --color-text: #e6ecf2;
        --color-muted: #9aa7b5;
        --color-primary: #5fb3e8;
        --color-primary-dark: #8fd0ff;
        --color-border: #262f39;
        --shadow: 0 4px 14px rgba(0, 0, 0, 0.4);
    }
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--color-text);
    background: var(--color-bg);
}

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

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

a:hover {
    color: var(--color-primary-dark);
}

a:focus-visible,
button:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1.25rem;
}

/* Header */
.site-header {
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 1.25rem;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.site-brand {
    font-size: 1.25rem;
    font-weight: 700;
    text-decoration: none;
    color: var(--color-text);
}

.site-nav a {
    margin-left: 1.25rem;
    text-decoration: none;
    font-weight: 500;
    color: var(--color-text);
}

/* Main */
.site-main {
    padding: 2rem 0 3rem;
}

/* Hero */
.hero {
    padding: 1.5rem 0 2.5rem;
    text-align: center;
}

.hero h1 {
    font-size: clamp(1.75rem, 4vw, 2.5rem);
    margin: 0 0 0.5rem;
}

.hero-slogan {
    color: var(--color-muted);
    font-size: 1.1rem;
    margin: 0;
}

/* Article grid (home + related articles) */
.article-list-section h2,
.related-articles h2 {
    font-size: 1.4rem;
    margin-bottom: 1rem;
}

.empty-state {
    color: var(--color-muted);
}

.article-grid,
.related-article-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 1.5rem;
}

.article-card,
.related-article-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
    display: flex;
    flex-direction: column;
    padding: 0;
}

.related-article-card {
    padding: 1.1rem;
}

.article-card-image img {
    aspect-ratio: 16 / 10;
    object-fit: cover;
    width: 100%;
}

.article-card-body {
    padding: 1.1rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    flex: 1;
}

.article-card-body h3,
.related-article-card h3 {
    margin: 0;
    font-size: 1.1rem;
    line-height: 1.35;
}

.article-card-body h3 a {
    text-decoration: none;
    color: var(--color-text);
}

.article-card-body h3 a:hover {
    color: var(--color-primary);
}

.article-card-excerpt,
.related-article-card p {
    color: var(--color-muted);
    font-size: 0.95rem;
    margin: 0;
    flex: 1;
}

.article-card-date {
    color: var(--color-muted);
    font-size: 0.85rem;
}

.related-articles {
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid var(--color-border);
}

/* Article page */
.article-page {
    max-width: var(--content-width);
    margin: 0 auto;
}

.article-header h1 {
    font-size: clamp(1.6rem, 4vw, 2.25rem);
    margin: 0 0 0.5rem;
    line-height: 1.25;
}

.article-meta {
    color: var(--color-muted);
    font-size: 0.9rem;
    margin: 0 0 1.25rem;
}

.article-featured-image {
    border-radius: var(--radius);
    margin-bottom: 1.5rem;
    width: 100%;
}

.article-body {
    font-size: 1.05rem;
    line-height: 1.75;
}

.article-body h2 {
    font-size: 1.4rem;
    margin-top: 2rem;
}

.article-body h3 {
    font-size: 1.15rem;
    margin-top: 1.5rem;
}

.article-body p {
    margin: 0 0 1.1rem;
}

.article-body img {
    border-radius: var(--radius);
    margin: 1.25rem 0;
}

/* Table of contents */
.table-of-contents {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 1rem 1.25rem;
    margin-bottom: 1.5rem;
    max-width: var(--content-width);
    margin-left: auto;
    margin-right: auto;
}

.table-of-contents h2 {
    font-size: 1rem;
    margin: 0 0 0.5rem;
    text-transform: uppercase;
    letter-spacing: 0.02em;
    color: var(--color-muted);
}

.table-of-contents ul {
    margin: 0;
    padding-left: 1.1rem;
}

.table-of-contents .toc-level-3 {
    margin-left: 1rem;
}

/* Footer */
.site-footer {
    border-top: 1px solid var(--color-border);
    padding: 1.5rem 0;
    text-align: center;
    color: var(--color-muted);
    font-size: 0.9rem;
}

/* Ad slots */
.adsbygoogle {
    margin: 1.5rem auto;
}

/* Mobile */
@media (max-width: 600px) {
    .header-inner {
        flex-direction: column;
        align-items: flex-start;
    }

    .site-nav {
        display: flex;
        gap: 0.5rem;
    }

    .site-nav a {
        margin-left: 0;
    }

    .article-grid,
    .related-article-list {
        grid-template-columns: 1fr;
    }
}