/* ===== CSS Variables ===== */
:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --primary-light: #dbeafe;
    --accent: #7c3aed;
    --bg: #f8fafc;
    --bg-card: #ffffff;
    --bg-dark: #1e293b;
    --text: #1e293b;
    --text-secondary: #64748b;
    --text-light: #94a3b8;
    --border: #e2e8f0;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow: 0 4px 6px -1px rgba(0,0,0,0.07), 0 2px 4px -2px rgba(0,0,0,0.05);
    --shadow-lg: 0 10px 25px -3px rgba(0,0,0,0.08), 0 4px 6px -4px rgba(0,0,0,0.05);
    --radius: 12px;
    --radius-sm: 8px;
    --transition: all 0.25s ease;
    --max-width: 1200px;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

a { color: inherit; text-decoration: none; }
ul { list-style: none; }
img { max-width: 100%; height: auto; }

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

/* ===== Header ===== */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(255,255,255,0.85);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
}

.navbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 1.25rem;
    font-weight: 800;
    color: var(--primary);
    letter-spacing: -0.5px;
}

.logo-icon { font-size: 1.4rem; }

.nav-links {
    display: flex;
    gap: 32px;
}

.nav-links a {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-secondary);
    transition: var(--transition);
    position: relative;
}

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

.nav-links a.active::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--primary);
    border-radius: 2px;
}

.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.menu-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text);
    border-radius: 2px;
    transition: var(--transition);
}

/* ===== Hero ===== */
.hero {
    background: linear-gradient(135deg, #eff6ff 0%, #f0f9ff 50%, #faf5ff 100%);
    padding: 80px 0 60px;
    text-align: center;
}

.hero-title {
    font-size: 2.75rem;
    font-weight: 900;
    letter-spacing: -1.5px;
    background: linear-gradient(135deg, var(--primary) 0%, var(--accent) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 16px;
}

.hero-subtitle {
    font-size: 1.15rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto 32px;
}

.hero-search {
    max-width: 500px;
    margin: 0 auto;
}

.search-input {
    width: 100%;
    padding: 14px 20px;
    font-size: 1rem;
    border: 2px solid var(--border);
    border-radius: 999px;
    outline: none;
    transition: var(--transition);
    background: white;
}

.search-input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 4px var(--primary-light);
}

/* ===== Categories ===== */
.categories {
    padding: 64px 0;
}

.section-title {
    font-size: 1.75rem;
    font-weight: 800;
    margin-bottom: 32px;
    letter-spacing: -0.5px;
}

.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 20px;
}

.category-card {
    background: var(--bg-card);
    padding: 28px 20px;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    text-align: center;
    transition: var(--transition);
    cursor: pointer;
}

.category-card:hover {
    border-color: var(--primary);
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

.category-icon {
    font-size: 2.5rem;
    margin-bottom: 12px;
}

.category-card h3 {
    font-size: 1.05rem;
    font-weight: 700;
    margin-bottom: 6px;
}

.category-card p {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* ===== Articles ===== */
.latest-articles {
    padding: 64px 0;
    background: var(--bg-card);
}

.section-header {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 32px;
    gap: 16px;
}

.filter-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.filter-tag {
    padding: 6px 16px;
    font-size: 0.85rem;
    font-weight: 500;
    border: 1px solid var(--border);
    border-radius: 999px;
    background: transparent;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
}

.filter-tag:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.filter-tag.active {
    background: var(--primary);
    border-color: var(--primary);
    color: white;
}

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

.article-card {
    background: var(--bg);
    border-radius: var(--radius);
    overflow: hidden;
    border: 1px solid var(--border);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
}

.article-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
    border-color: var(--primary-light);
}

.article-card-image {
    height: 180px;
    background: linear-gradient(135deg, var(--primary-light) 0%, #ede9fe 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 3rem;
}

.article-card-body {
    padding: 20px;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.article-tag {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--primary);
    background: var(--primary-light);
    padding: 3px 10px;
    border-radius: 999px;
    margin-bottom: 10px;
    align-self: flex-start;
}

.article-card h3 {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 8px;
    line-height: 1.4;
    color: var(--text);
}

.article-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 14px;
    flex: 1;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.article-meta {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.8rem;
    color: var(--text-light);
}

.article-meta span:not(:last-child)::after {
    content: "\2022";
    margin-left: 8px;
}

/* ===== Load More ===== */
.load-more {
    text-align: center;
    margin-top: 40px;
}

.btn-load-more {
    padding: 12px 40px;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--primary);
    background: var(--primary-light);
    border: none;
    border-radius: 999px;
    cursor: pointer;
    transition: var(--transition);
}

.btn-load-more:hover {
    background: var(--primary);
    color: white;
}

/* ===== Newsletter ===== */
.newsletter {
    padding: 64px 0;
}

.newsletter-box {
    background: linear-gradient(135deg, #1e293b 0%, #334155 100%);
    border-radius: var(--radius);
    padding: 48px 32px;
    text-align: center;
    color: white;
}

.newsletter-box h2 {
    font-size: 1.5rem;
    font-weight: 800;
    margin-bottom: 12px;
}

.newsletter-box p {
    color: #cbd5e1;
    margin-bottom: 8px;
}

.newsletter-hint {
    font-size: 0.9rem !important;
    color: #94a3b8 !important;
}

/* ===== Footer ===== */
.site-footer {
    background: var(--bg-dark);
    color: #cbd5e1;
    padding: 56px 0 24px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 32px;
}

.footer-col .logo {
    color: white;
    margin-bottom: 12px;
}

.footer-desc {
    font-size: 0.9rem;
    color: #94a3b8;
}

.footer-col h4 {
    color: white;
    font-size: 0.95rem;
    font-weight: 700;
    margin-bottom: 14px;
}

.footer-col ul li {
    margin-bottom: 8px;
}

.footer-col ul a {
    font-size: 0.9rem;
    color: #94a3b8;
    transition: var(--transition);
}

.footer-col ul a:hover {
    color: white;
}

.footer-bottom {
    border-top: 1px solid #334155;
    padding-top: 24px;
    text-align: center;
}

.footer-bottom p {
    font-size: 0.85rem;
    color: #64748b;
}

/* ===== Article Page ===== */
.article-hero {
    background: linear-gradient(135deg, #eff6ff 0%, #f0f9ff 100%);
    padding: 48px 0 40px;
    border-bottom: 1px solid var(--border);
}

.article-breadcrumb {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 16px;
}

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

.article-hero h1 {
    font-size: 2.25rem;
    font-weight: 800;
    line-height: 1.3;
    margin-bottom: 16px;
    letter-spacing: -0.5px;
}

.article-hero-meta {
    display: flex;
    align-items: center;
    gap: 16px;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.article-content {
    padding: 56px 0;
}

.article-body {
    max-width: 760px;
    margin: 0 auto;
}

.article-body h2 {
    font-size: 1.5rem;
    font-weight: 800;
    margin: 36px 0 16px;
    letter-spacing: -0.5px;
}

.article-body h3 {
    font-size: 1.2rem;
    font-weight: 700;
    margin: 28px 0 12px;
}

.article-body p {
    margin-bottom: 18px;
    color: #334155;
    font-size: 1.05rem;
    line-height: 1.85;
}

.article-body ul,
.article-body ol {
    margin: 0 0 18px 24px;
}

.article-body li {
    margin-bottom: 8px;
    color: #334155;
    line-height: 1.8;
}

.article-body code {
    font-family: "Fira Code", "Cascadia Code", "Consolas", monospace;
    background: #f1f5f9;
    color: var(--accent);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 0.9em;
}

.article-body pre {
    background: #1e293b;
    color: #e2e8f0;
    padding: 20px;
    border-radius: var(--radius-sm);
    overflow-x: auto;
    margin: 20px 0;
    font-size: 0.9rem;
    line-height: 1.6;
}

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

.article-body blockquote {
    border-left: 4px solid var(--primary);
    padding: 8px 0 8px 20px;
    margin: 20px 0;
    color: var(--text-secondary);
    font-style: italic;
    background: var(--primary-light);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    padding: 16px 20px;
}

.article-body img {
    border-radius: var(--radius-sm);
    margin: 20px 0;
}

.article-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin: 32px 0;
    padding-top: 24px;
    border-top: 1px solid var(--border);
}

.article-tags .tag {
    font-size: 0.8rem;
    padding: 4px 12px;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 999px;
    color: var(--text-secondary);
}

.article-nav {
    display: flex;
    justify-content: space-between;
    gap: 16px;
    margin-top: 48px;
    padding-top: 32px;
    border-top: 1px solid var(--border);
}

.article-nav a {
    padding: 12px 20px;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    transition: var(--transition);
    max-width: 48%;
}

.article-nav a:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.article-nav .nav-label {
    font-size: 0.75rem;
    color: var(--text-light);
    display: block;
    margin-bottom: 4px;
}

.article-nav .nav-title {
    font-size: 0.95rem;
    font-weight: 600;
}

/* ===== About Page ===== */
.about-hero {
    background: linear-gradient(135deg, #eff6ff 0%, #f0f9ff 50%, #faf5ff 100%);
    padding: 64px 0;
    text-align: center;
}

.about-content {
    padding: 56px 0;
}

.about-body {
    max-width: 760px;
    margin: 0 auto;
}

.about-body h2 {
    font-size: 1.5rem;
    font-weight: 800;
    margin: 36px 0 16px;
}

.about-body p {
    margin-bottom: 18px;
    color: #334155;
    font-size: 1.05rem;
    line-height: 1.85;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: 16px 24px;
        border-bottom: 1px solid var(--border);
        gap: 16px;
    }

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

    .menu-toggle {
        display: flex;
    }

    .hero-title {
        font-size: 2rem;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

    .section-header {
        flex-direction: column;
        align-items: flex-start;
    }

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

    .footer-grid {
        grid-template-columns: 1fr;
        gap: 24px;
    }

    .article-hero h1 {
        font-size: 1.5rem;
    }

    .article-body {
        font-size: 0.95rem;
    }
}