/* ========== SEO 辅助类 ========== */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* ========== 精致配色系统 ========== */
:root {
    --primary: #6366f1;
    --primary-light: #818cf8;
    --primary-dark: #4f46e5;
    --primary-bg: rgba(99,102,241,0.08);
    
    --accent: #f59e0b;
    --success: #10b981;
    --danger: #ef4444;
    
    --gray-50: #fafbfc;
    --gray-100: #f4f5f7;
    --gray-200: #e4e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    
    --white: #ffffff;
    --bg: #f5f7fa;
    --card-bg: #ffffff;
    
    --shadow-xs: 0 1px 2px rgba(0,0,0,0.04);
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.06);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.12);
    --shadow-xl: 0 16px 48px rgba(0,0,0,0.16);
    --shadow-primary: 0 8px 24px rgba(99,102,241,0.25);
    
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    
    --transition: 200ms cubic-bezier(0.4,0,0.2,1);
}

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

html { scroll-behavior: smooth; }

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Noto Sans SC', sans-serif;
    background: var(--bg);
    color: var(--gray-700);
    line-height: 1.6;
    min-height: 100vh;
    position: relative;
    overflow-x: hidden;
}

/* 背景装饰 */
body::before {
    content: '';
    position: fixed;
    top: -50%;
    right: -20%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(99,102,241,0.08) 0%, transparent 70%);
    pointer-events: none;
    z-index: -1;
}

body::after {
    content: '';
    position: fixed;
    bottom: -30%;
    left: -10%;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(245,158,11,0.06) 0%, transparent 70%);
    pointer-events: none;
    z-index: -1;
}

/* ========== 头部 ========== */
header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 1rem 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-lg);
}

.header-inner {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    gap: 2rem;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    text-decoration: none;
    flex-shrink: 0;
}

.logo-icon {
    font-size: 1.8rem;
    filter: drop-shadow(0 2px 4px rgba(0,0,0,0.2));
    animation: bounce 2s ease infinite;
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-3px); }
}

.logo-text {
    color: var(--white);
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: 0.02em;
    text-shadow: 0 2px 8px rgba(0,0,0,0.15);
}

/* 搜索框 */
.search-wrapper {
    flex: 1;
    max-width: 520px;
    display: flex;
    align-items: center;
    background: rgba(255,255,255,0.95);
    backdrop-filter: blur(12px);
    border-radius: var(--radius-xl);
    padding: 0.4rem;
    box-shadow: 0 4px 24px rgba(0,0,0,0.15);
    border: 1px solid rgba(255,255,255,0.3);
}

.search-icon {
    padding: 0 0.8rem 0 0.6rem;
    font-size: 1.1rem;
    opacity: 0.5;
}

.search-wrapper input {
    flex: 1;
    border: none;
    outline: none;
    background: transparent;
    padding: 0.5rem 0;
    font-size: 0.95rem;
    color: var(--gray-800);
}

.search-wrapper input::placeholder {
    color: var(--gray-400);
}

.search-wrapper button {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: var(--white);
    border: none;
    padding: 0.5rem 1.3rem;
    border-radius: var(--radius-lg);
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    box-shadow: 0 2px 8px rgba(99,102,241,0.3);
}

.search-wrapper button:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(99,102,241,0.4);
}

.search-wrapper button:active {
    transform: translateY(0) scale(0.98);
}

/* ========== 主体 ========== */
main {
    display: flex;
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem;
    gap: 2rem;
    min-height: calc(100vh - 180px);
}

/* ========== 侧边栏 ========== */
.sidebar {
    width: 220px;
    flex-shrink: 0;
    position: sticky;
    top: 88px;
    align-self: start;
}

.sidebar-title {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem 1.25rem;
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--gray-500);
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.category-list {
    list-style: none;
    background: var(--card-bg);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-sm);
    overflow: hidden;
    border: 1px solid var(--gray-100);
}

.category-list li {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.9rem 1.25rem;
    cursor: pointer;
    transition: all var(--transition);
    border-left: 3px solid transparent;
    color: var(--gray-600);
    position: relative;
}

.category-list li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 0;
    background: linear-gradient(90deg, var(--primary-bg) 0%, transparent 100%);
    transition: width var(--transition);
}

.category-list li:hover {
    color: var(--gray-800);
}

.category-list li:hover::before {
    width: 100%;
}

.category-list li.active {
    border-left-color: var(--primary);
    color: var(--primary);
    font-weight: 600;
    background: var(--primary-bg);
}

.cat-icon {
    font-size: 1.15rem;
    width: 24px;
    text-align: center;
}

.cat-name {
    font-size: 0.92rem;
}

/* ========== 内容区 ========== */
.content {
    flex: 1;
    min-width: 0;
}

/* ========== 状态提示 ========== */
.loading-state, .empty-state, .error-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 4rem 2rem;
    text-align: center;
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
}

.loading-spinner {
    width: 44px;
    height: 44px;
    border: 3px solid var(--gray-100);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin-bottom: 1rem;
}

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

.loading-state p, .empty-state p {
    color: var(--gray-500);
    font-size: 0.95rem;
}

.empty-icon, .error-icon {
    font-size: 3.5rem;
    margin-bottom: 0.75rem;
    opacity: 0.7;
}

.error-state p {
    color: var(--danger);
    margin-bottom: 1rem;
    font-size: 0.95rem;
}

.retry-btn {
    background: var(--primary);
    color: var(--white);
    border: none;
    padding: 0.6rem 1.5rem;
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
}

.retry-btn:hover {
    background: var(--primary-dark);
    transform: translateY(-1px);
}

/* ========== 站点网格 ========== */
.sites-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
}

/* ========== 站点卡片 ========== */
.site-card {
    background: var(--card-bg);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition);
    border: 1px solid var(--gray-100);
    display: flex;
    flex-direction: column;
    position: relative;
    animation: cardIn 0.4s ease forwards;
    opacity: 0;
}

@keyframes cardIn {
    from {
        opacity: 0;
        transform: translateY(20px) scale(0.98);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

.site-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary) 0%, var(--primary-light) 50%, var(--accent) 100%);
    opacity: 0;
    transition: opacity var(--transition);
}

.site-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: transparent;
}

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

.card-header {
    padding: 1.25rem 1.25rem 0.75rem;
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
}

.card-icon {
    width: 44px;
    height: 44px;
    border-radius: var(--radius-sm);
    background: linear-gradient(135deg, var(--primary-bg) 0%, rgba(99,102,241,0.15) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    flex-shrink: 0;
}

.card-title-wrap {
    flex: 1;
    min-width: 0;
}

.site-card h2 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--gray-800);
    margin-bottom: 0.25rem;
    line-height: 1.4;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.category-badge {
    display: inline-flex;
    align-items: center;
    padding: 0.15rem 0.5rem;
    border-radius: 20px;
    font-size: 0.7rem;
    font-weight: 500;
    background: var(--gray-100);
    color: var(--gray-500);
}

.site-card[data-category="网站"] .category-badge {
    background: rgba(99,102,241,0.1);
    color: var(--primary);
}

.site-card[data-category="社区"] .category-badge {
    background: rgba(16,185,129,0.1);
    color: var(--success);
}

.site-card[data-category="游戏"] .category-badge {
    background: rgba(245,158,11,0.1);
    color: var(--accent);
}

.card-body {
    padding: 0 1.25rem 0.75rem;
}

.site-card p {
    color: var(--gray-500);
    font-size: 0.85rem;
    line-height: 1.6;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.card-footer {
    padding: 0.75rem 1.25rem 1.25rem;
    margin-top: auto;
}

.site-card a {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: var(--white);
    text-decoration: none;
    padding: 0.55rem 1rem;
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    font-weight: 500;
    transition: all var(--transition);
    box-shadow: 0 2px 8px rgba(99,102,241,0.2);
}

.site-card a::before {
    content: '🚀';
    font-size: 0.8rem;
}

.site-card a:hover {
    transform: scale(1.02);
    box-shadow: var(--shadow-primary);
}

/* ========== 页脚 ========== */
footer {
    background: linear-gradient(135deg, var(--gray-800) 0%, var(--gray-900) 100%);
    padding: 1.5rem;
    text-align: center;
    margin-top: auto;
}

footer p {
    color: var(--gray-400);
    font-size: 0.85rem;
}

/* ========== 响应式 ========== */
@media (max-width: 1024px) {
    main { flex-direction: column; }
    .sidebar {
        width: 100%;
        position: static;
    }
    .sidebar-title { display: none; }
    .category-list {
        display: flex;
        flex-wrap: wrap;
        padding: 0.5rem;
        gap: 0.5rem;
        border-radius: var(--radius-md);
    }
    .category-list li {
        border-left: none;
        border-radius: var(--radius-sm);
        padding: 0.6rem 1rem;
    }
    .category-list li::before { display: none; }
    .category-list li.active {
        background: var(--primary);
        color: var(--white);
        border-left: none;
    }
}

@media (max-width: 768px) {
    header { padding: 0.8rem 1rem; }
    .header-inner { flex-wrap: wrap; gap: 1rem; }
    .logo-icon { font-size: 1.5rem; }
    .logo-text { font-size: 1.1rem; }
    .search-wrapper {
        max-width: 100%;
        flex-basis: 100%;
    }
    main { padding: 1.5rem 1rem; gap: 1rem; }
    .sites-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    .site-card { animation-delay: 0.05s !important; }
}

/* 动画延迟 */
.site-card:nth-child(1) { animation-delay: 0.02s; }
.site-card:nth-child(2) { animation-delay: 0.04s; }
.site-card:nth-child(3) { animation-delay: 0.06s; }
.site-card:nth-child(4) { animation-delay: 0.08s; }
.site-card:nth-child(5) { animation-delay: 0.10s; }
.site-card:nth-child(6) { animation-delay: 0.12s; }
.site-card:nth-child(7) { animation-delay: 0.14s; }
.site-card:nth-child(8) { animation-delay: 0.16s; }