/* ===== CSS Variables ===== */
:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-card: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    --border-color: #e2e8f0;
    --accent: #6366f1;
    --accent-hover: #4f46e5;
    --accent-light: #eef2ff;
    --gradient-1: #6366f1;
    --gradient-2: #8b5cf6;
    --gradient-3: #a855f7;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -2px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -4px rgba(0,0,0,0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 8px 10px -6px rgba(0,0,0,0.1);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-card: #1e293b;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --border-color: #334155;
    --accent: #818cf8;
    --accent-hover: #6366f1;
    --accent-light: #1e1b4b;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.4);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.4);
    --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.4);
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    transition: background var(--transition), color var(--transition);
    overflow-x: hidden;
}

a {
    text-decoration: none;
    color: inherit;
}

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

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== Navbar ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255,255,255,0.8);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid transparent;
    transition: all var(--transition);
}

[data-theme="dark"] .navbar {
    background: rgba(15,23,42,0.8);
}

.navbar.scrolled {
    border-bottom-color: var(--border-color);
    box-shadow: var(--shadow-sm);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
}

.logo-icon {
    font-size: 1.5rem;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 8px;
}

.nav-link {
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
    transition: all var(--transition);
}

.nav-link:hover,
.nav-link.active {
    color: var(--accent);
    background: var(--accent-light);
}

.theme-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    background: var(--bg-card);
    cursor: pointer;
    font-size: 1.2rem;
    transition: all var(--transition);
}

.theme-toggle:hover {
    border-color: var(--accent);
    background: var(--accent-light);
}

.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.mobile-menu-btn span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: all var(--transition);
}

.mobile-menu {
    position: fixed;
    top: 64px;
    left: 0;
    right: 0;
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    padding: 16px 24px;
    display: none;
    flex-direction: column;
    gap: 8px;
    z-index: 999;
    transform: translateY(-100%);
    transition: transform var(--transition);
}

.mobile-menu.active {
    transform: translateY(0);
}

.mobile-menu a {
    padding: 12px 16px;
    border-radius: var(--radius-sm);
    font-weight: 500;
    color: var(--text-secondary);
    transition: all var(--transition);
}

.mobile-menu a:hover {
    background: var(--accent-light);
    color: var(--accent);
}

/* ===== Hero Section ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
    padding: 120px 24px 80px;
}

.hero-bg {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse 80% 80% at 50% -20%, rgba(99,102,241,0.15), transparent),
        radial-gradient(ellipse 60% 60% at 80% 80%, rgba(139,92,246,0.1), transparent);
    pointer-events: none;
}

.hero-content {
    text-align: center;
    position: relative;
    z-index: 1;
    max-width: 700px;
}

.hero-badge {
    display: inline-block;
    padding: 6px 16px;
    background: var(--accent-light);
    color: var(--accent);
    border-radius: 50px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 24px;
    letter-spacing: 0.5px;
}

.hero-title {
    font-size: clamp(2.5rem, 6vw, 4rem);
    font-weight: 800;
    line-height: 1.15;
    margin-bottom: 20px;
    letter-spacing: -0.02em;
}

.gradient-text {
    background: linear-gradient(135deg, var(--gradient-1), var(--gradient-2), var(--gradient-3));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 12px;
    font-weight: 500;
}

.hero-desc {
    font-size: 1rem;
    color: var(--text-muted);
    max-width: 500px;
    margin: 0 auto 36px;
}

.hero-actions {
    display: flex;
    gap: 12px;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 48px;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 28px;
    border-radius: 50px;
    font-size: 0.95rem;
    font-weight: 600;
    transition: all var(--transition);
    cursor: pointer;
    border: none;
}

.btn-primary {
    background: linear-gradient(135deg, var(--gradient-1), var(--gradient-2));
    color: #fff;
    box-shadow: 0 4px 15px rgba(99,102,241,0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(99,102,241,0.5);
}

.btn-primary .arrow {
    transition: transform var(--transition);
}

.btn-primary:hover .arrow {
    transform: translateX(4px);
}

.btn-secondary {
    background: var(--bg-card);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    border-color: var(--accent);
    color: var(--accent);
    background: var(--accent-light);
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 48px;
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
}

.stat-number {
    font-size: 2rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--gradient-1), var(--gradient-2));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-muted);
}

.scroll-indicator {
    position: absolute;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    color: var(--text-muted);
    font-size: 0.8rem;
    animation: float 2s ease-in-out infinite;
}

.scroll-arrow {
    font-size: 1.2rem;
}

@keyframes float {
    0%, 100% { transform: translateX(-50%) translateY(0); }
    50% { transform: translateX(-50%) translateY(8px); }
}

/* ===== Articles Section ===== */
.articles-section {
    padding: 100px 0;
    background: var(--bg-secondary);
}

.section-header {
    text-align: center;
    margin-bottom: 48px;
}

.section-title {
    font-size: 2rem;
    font-weight: 800;
    margin-bottom: 8px;
}

.section-desc {
    color: var(--text-muted);
    font-size: 1rem;
}

/* Filter Bar */
.filter-bar {
    margin-bottom: 40px;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.search-box {
    position: relative;
    max-width: 480px;
    width: 100%;
    margin: 0 auto;
}

.search-icon {
    position: absolute;
    left: 16px;
    top: 50%;
    transform: translateY(-50%);
    width: 20px;
    height: 20px;
    color: var(--text-muted);
    pointer-events: none;
}

.search-box input {
    width: 100%;
    padding: 14px 20px 14px 48px;
    border: 1px solid var(--border-color);
    border-radius: 50px;
    background: var(--bg-card);
    color: var(--text-primary);
    font-size: 0.95rem;
    outline: none;
    transition: all var(--transition);
}

.search-box input:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(99,102,241,0.15);
}

.search-box input::placeholder {
    color: var(--text-muted);
}

.tag-filters {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 8px;
}

.tag-btn {
    padding: 6px 16px;
    border: 1px solid var(--border-color);
    border-radius: 50px;
    background: var(--bg-card);
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition);
}

.tag-btn:hover {
    border-color: var(--accent);
    color: var(--accent);
}

.tag-btn.active {
    background: var(--accent);
    border-color: var(--accent);
    color: #fff;
}

/* Articles Grid */
.articles-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
    gap: 24px;
}

.article-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 28px;
    transition: all var(--transition);
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.article-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--gradient-1), var(--gradient-2), var(--gradient-3));
    opacity: 0;
    transition: opacity var(--transition);
}

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

.article-card:hover::before {
    opacity: 1;
}

.article-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    margin-bottom: 16px;
}

.article-tag {
    padding: 3px 10px;
    background: var(--accent-light);
    color: var(--accent);
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 600;
}

.article-title {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 10px;
    line-height: 1.4;
    color: var(--text-primary);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.article-excerpt {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 16px;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    line-height: 1.6;
}

.article-meta {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 0.8rem;
    color: var(--text-muted);
    padding-top: 16px;
    border-top: 1px solid var(--border-color);
}

.article-date {
    display: flex;
    align-items: center;
    gap: 6px;
}

.article-read-more {
    display: flex;
    align-items: center;
    gap: 4px;
    color: var(--accent);
    font-weight: 600;
    font-size: 0.85rem;
}

.article-read-more .arrow-icon {
    transition: transform var(--transition);
}

.article-card:hover .arrow-icon {
    transform: translateX(3px);
}

.no-results {
    grid-column: 1 / -1;
    text-align: center;
    padding: 60px 20px;
    color: var(--text-muted);
}

.no-results .no-results-icon {
    font-size: 3rem;
    margin-bottom: 16px;
}

.no-results h3 {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

/* ===== Article Detail Modal ===== */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.6);
    backdrop-filter: blur(4px);
    z-index: 2000;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition);
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--bg-primary);
    border-radius: var(--radius-xl);
    max-width: 800px;
    width: 100%;
    max-height: 85vh;
    overflow-y: auto;
    box-shadow: var(--shadow-xl);
    transform: translateY(20px);
    transition: transform var(--transition);
}

.modal-overlay.active .modal {
    transform: translateY(0);
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 24px 32px;
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    background: var(--bg-primary);
    z-index: 1;
}

.modal-title {
    font-size: 1.3rem;
    font-weight: 700;
}

.modal-close {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border: 1px solid var(--border-color);
    border-radius: 50%;
    background: var(--bg-card);
    cursor: pointer;
    font-size: 1.1rem;
    color: var(--text-secondary);
    transition: all var(--transition);
}

.modal-close:hover {
    background: var(--accent-light);
    color: var(--accent);
    border-color: var(--accent);
}

.modal-body {
    padding: 32px;
}

.modal-body h1, .modal-body h2, .modal-body h3 {
    margin: 24px 0 12px;
    line-height: 1.4;
}

.modal-body h1 { font-size: 1.6rem; }
.modal-body h2 { font-size: 1.35rem; }
.modal-body h3 { font-size: 1.15rem; }

.modal-body p {
    margin-bottom: 12px;
    line-height: 1.8;
}

.modal-body ul, .modal-body ol {
    margin: 12px 0;
    padding-left: 24px;
}

.modal-body li {
    margin-bottom: 6px;
    line-height: 1.7;
}

.modal-body code {
    background: var(--bg-secondary);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 0.9em;
    font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
}

.modal-body pre {
    background: var(--bg-secondary);
    padding: 20px;
    border-radius: var(--radius-md);
    overflow-x: auto;
    margin: 16px 0;
    border: 1px solid var(--border-color);
}

.modal-body pre code {
    background: none;
    padding: 0;
}

.modal-body blockquote {
    border-left: 3px solid var(--accent);
    padding: 8px 16px;
    margin: 16px 0;
    background: var(--accent-light);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    color: var(--text-secondary);
}

.modal-body img {
    border-radius: var(--radius-md);
    margin: 16px 0;
}

.modal-body table {
    width: 100%;
    border-collapse: collapse;
    margin: 16px 0;
}

.modal-body th, .modal-body td {
    border: 1px solid var(--border-color);
    padding: 10px 14px;
    text-align: left;
}

.modal-body th {
    background: var(--bg-secondary);
    font-weight: 600;
}

.modal-body a {
    color: var(--accent);
    text-decoration: underline;
}

.modal-footer {
    padding: 20px 32px;
    border-top: 1px solid var(--border-color);
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.modal-tag {
    padding: 4px 12px;
    background: var(--accent-light);
    color: var(--accent);
    border-radius: 50px;
    font-size: 0.8rem;
    font-weight: 600;
}

/* ===== About Section ===== */
.about-section {
    padding: 100px 0;
}

.about-card {
    max-width: 560px;
    margin: 0 auto;
    text-align: center;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    padding: 48px 40px;
    box-shadow: var(--shadow-md);
}

.about-avatar {
    margin-bottom: 24px;
}

.avatar-placeholder {
    width: 80px;
    height: 80px;
    margin: 0 auto;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--gradient-1), var(--gradient-2));
    color: #fff;
    font-size: 2rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
}

.about-name {
    font-size: 1.5rem;
    font-weight: 800;
    margin-bottom: 8px;
}

.about-role {
    font-size: 0.95rem;
    color: var(--accent);
    font-weight: 600;
    margin-bottom: 20px;
}

.about-bio {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.8;
    margin-bottom: 28px;
}

.about-links {
    display: flex;
    justify-content: center;
    gap: 12px;
}

.about-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 44px;
    border: 1px solid var(--border-color);
    border-radius: 50%;
    color: var(--text-secondary);
    transition: all var(--transition);
}

.about-link svg {
    width: 20px;
    height: 20px;
}

.about-link:hover {
    border-color: var(--accent);
    color: var(--accent);
    background: var(--accent-light);
    transform: translateY(-2px);
}

/* ===== Footer ===== */
.footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    padding: 48px 0 24px;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 24px;
    margin-bottom: 32px;
}

.footer-logo {
    font-size: 1.1rem;
    font-weight: 700;
}

.footer-brand p {
    color: var(--text-muted);
    font-size: 0.85rem;
    margin-top: 4px;
}

.visitor-counter {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 4px;
}

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

.visitor-number {
    font-size: 1.5rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--gradient-1), var(--gradient-2));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.footer-bottom {
    text-align: center;
    padding-top: 24px;
    border-top: 1px solid var(--border-color);
    color: var(--text-muted);
    font-size: 0.85rem;
}

/* ===== Loading Animation ===== */
.loading {
    grid-column: 1 / -1;
    text-align: center;
    padding: 60px;
    color: var(--text-muted);
}

.loading::after {
    content: '';
    display: inline-block;
    width: 24px;
    height: 24px;
    border: 2px solid var(--border-color);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
    margin-left: 8px;
    vertical-align: middle;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* ===== Back to Top ===== */
.back-to-top {
    position: fixed;
    bottom: 32px;
    right: 32px;
    width: 44px;
    height: 44px;
    border: 1px solid var(--border-color);
    border-radius: 50%;
    background: var(--bg-card);
    color: var(--text-secondary);
    font-size: 1.2rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-md);
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: all var(--transition);
    z-index: 900;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    border-color: var(--accent);
    color: var(--accent);
    background: var(--accent-light);
    transform: translateY(-4px);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .mobile-menu-btn {
        display: flex;
    }

    .mobile-menu {
        display: flex;
    }

    .hero-stats {
        gap: 32px;
    }

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

    .article-card {
        padding: 22px;
    }

    .about-card {
        padding: 32px 24px;
    }

    .footer-content {
        flex-direction: column;
        text-align: center;
    }

    .visitor-counter {
        align-items: center;
    }

    .modal {
        max-height: 90vh;
    }

    .modal-body {
        padding: 20px;
    }
}

@media (max-width: 480px) {
    .hero-stats {
        gap: 20px;
    }

    .stat-number {
        font-size: 1.5rem;
    }

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

/* ===== Print ===== */
@media print {
    .navbar, .footer, .back-to-top, .modal-overlay {
        display: none;
    }
}