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

:root {
    --color-bg: #ffffff;
    --color-text: #1a1a1a;
    --color-text-secondary: #6b7280;
    --color-border: #e5e7eb;
    --color-accent: #2563eb;
    --color-accent-hover: #1d4ed8;
    --color-card-bg: #ffffff;
    --color-tag-bg: #f3f4f6;
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-serif: 'Georgia', 'Times New Roman', serif;
    --max-width: 1100px;
    --max-width-article: 720px;
}

html {
    font-size: 16px;
    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;
}

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

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

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

/* ===== Header ===== */
.site-header {
    border-bottom: 1px solid var(--color-border);
    padding: 1rem 1.5rem;
    position: sticky;
    top: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    z-index: 100;
}

.header-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    text-decoration: none;
    color: var(--color-text);
}

.logo img {
    height: 36px;
    width: auto;
}

.logo span {
    font-weight: 700;
    font-size: 1.125rem;
    letter-spacing: -0.02em;
}

.nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
}

.nav-links a {
    color: var(--color-text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    transition: color 0.2s;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--color-text);
}

/* Mobile menu */
.menu-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

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

/* ===== Hero / Page Header ===== */
.page-hero {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 4rem 1.5rem 2rem;
}

.page-hero h1 {
    font-size: 2.5rem;
    font-weight: 800;
    letter-spacing: -0.03em;
    line-height: 1.2;
    margin-bottom: 0.75rem;
}

.page-hero p {
    color: var(--color-text-secondary);
    font-size: 1.125rem;
    max-width: 600px;
}

/* ===== Article Grid ===== */
.articles-grid {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 1rem 1.5rem 4rem;
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 2rem;
}

.article-card {
    border: 1px solid var(--color-border);
    border-radius: 12px;
    overflow: hidden;
    transition: transform 0.2s, box-shadow 0.2s;
    background: var(--color-card-bg);
}

.article-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
}

.article-card a {
    text-decoration: none;
    color: inherit;
}

.article-card-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
    background: var(--color-tag-bg);
}

.article-card-body {
    padding: 1.25rem;
}

.article-card-meta {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 0.75rem;
    font-size: 0.8rem;
    color: var(--color-text-secondary);
}

.article-card-tag {
    background: var(--color-tag-bg);
    padding: 0.2rem 0.6rem;
    border-radius: 4px;
    font-weight: 500;
}

.article-card-body h2 {
    font-size: 1.2rem;
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: 0.5rem;
    letter-spacing: -0.01em;
}

.article-card-body p {
    color: var(--color-text-secondary);
    font-size: 0.9rem;
    line-height: 1.5;
}

/* ===== Article Detail ===== */
.article-header {
    max-width: var(--max-width-article);
    margin: 0 auto;
    padding: 3rem 1.5rem 1.5rem;
}

.article-header .back-link {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    color: var(--color-text-secondary);
    font-size: 0.875rem;
    margin-bottom: 2rem;
}

.article-header .back-link:hover {
    color: var(--color-text);
}

.article-meta {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
    font-size: 0.85rem;
    color: var(--color-text-secondary);
}

.article-tag {
    background: var(--color-tag-bg);
    padding: 0.25rem 0.75rem;
    border-radius: 4px;
    font-weight: 500;
    font-size: 0.8rem;
}

.article-header h1 {
    font-size: 2.25rem;
    font-weight: 800;
    line-height: 1.2;
    letter-spacing: -0.03em;
    margin-bottom: 1rem;
}

.article-header .article-excerpt {
    font-size: 1.15rem;
    color: var(--color-text-secondary);
    line-height: 1.6;
}

.article-featured-image {
    max-width: var(--max-width-article);
    margin: 1.5rem auto;
    padding: 0 1.5rem;
}

.article-featured-image img {
    width: 100%;
    border-radius: 12px;
}

/* Article Content */
.article-content {
    max-width: var(--max-width-article);
    margin: 0 auto;
    padding: 1rem 1.5rem 4rem;
    font-family: var(--font-serif);
    font-size: 1.1rem;
    line-height: 1.8;
    color: #333;
}

.article-content h2 {
    font-family: var(--font-sans);
    font-size: 1.5rem;
    font-weight: 700;
    margin: 2.5rem 0 1rem;
    letter-spacing: -0.02em;
}

.article-content h3 {
    font-family: var(--font-sans);
    font-size: 1.2rem;
    font-weight: 600;
    margin: 2rem 0 0.75rem;
}

.article-content p {
    margin-bottom: 1.25rem;
}

.article-content ul,
.article-content ol {
    margin-bottom: 1.25rem;
    padding-left: 1.5rem;
}

.article-content li {
    margin-bottom: 0.4rem;
}

.article-content blockquote {
    border-left: 3px solid var(--color-accent);
    padding-left: 1.25rem;
    margin: 1.5rem 0;
    color: var(--color-text-secondary);
    font-style: italic;
}

.article-content code {
    font-family: 'SF Mono', 'Fira Code', monospace;
    background: var(--color-tag-bg);
    padding: 0.15rem 0.4rem;
    border-radius: 4px;
    font-size: 0.9em;
}

.article-content pre {
    background: #1a1a2e;
    color: #e0e0e0;
    padding: 1.25rem;
    border-radius: 8px;
    overflow-x: auto;
    margin-bottom: 1.5rem;
}

.article-content pre code {
    background: none;
    padding: 0;
    color: inherit;
}

.article-content a {
    color: var(--color-accent);
    text-decoration: underline;
    text-underline-offset: 2px;
}

.article-content img {
    border-radius: 8px;
    margin: 1.5rem 0;
}

/* ===== Share Buttons ===== */
.share-section {
    max-width: var(--max-width-article);
    margin: 0 auto;
    padding: 0 1.5rem 3rem;
    border-top: 1px solid var(--color-border);
    padding-top: 2rem;
}

.share-label {
    display: block;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--color-text-secondary);
    margin-bottom: 0.75rem;
}

.share-buttons {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    align-items: center;
}

.share-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.4rem;
    width: 40px;
    height: 40px;
    border-radius: 8px;
    border: 1px solid var(--color-border);
    background: var(--color-bg);
    color: var(--color-text-secondary);
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
    font-size: 0.8rem;
    font-family: var(--font-sans);
}

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

.share-copy {
    width: auto;
    padding: 0 0.75rem;
}

.share-copy.copied {
    border-color: #22c55e;
    color: #22c55e;
}

/* ===== Footer ===== */
.site-footer {
    border-top: 1px solid var(--color-border);
    padding: 2.5rem 1.5rem;
    text-align: center;
}

.footer-inner {
    max-width: var(--max-width);
    margin: 0 auto;
}

.footer-logo {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.75rem;
    color: var(--color-text);
    text-decoration: none;
}

.footer-logo img {
    height: 24px;
}

.footer-logo span {
    font-weight: 600;
    font-size: 0.9rem;
}

.site-footer p {
    font-size: 0.8rem;
    color: var(--color-text-secondary);
}

/* ===== 404 / Not Found ===== */
.not-found {
    max-width: var(--max-width-article);
    margin: 0 auto;
    padding: 6rem 1.5rem;
    text-align: center;
}

.not-found h1 {
    font-size: 2rem;
    margin-bottom: 1rem;
}

.not-found p {
    color: var(--color-text-secondary);
    margin-bottom: 2rem;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .menu-toggle {
        display: block;
    }

    .header-inner nav {
        position: absolute;
        right: 0;
        left: 0;
        top: 100%;
    }

    .nav-links {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--color-bg);
        flex-direction: column;
        padding: 1rem 1.5rem;
        gap: 1rem;
        border-bottom: 1px solid var(--color-border);
    }

    .nav-links.open {
        display: flex;
    }

    .page-hero {
        padding: 2.5rem 1.5rem 1.5rem;
    }

    .page-hero h1 {
        font-size: 1.75rem;
    }

    .articles-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    .article-header h1 {
        font-size: 1.75rem;
    }

    .article-content {
        font-size: 1rem;
    }
}