* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #0099cc;
    --primary-light: #00b8e6;
    --bg-color: #ffffff;
    --bg-card: #f8f9fa;
    --bg-card-hover: #f0f1f2;
    --text-primary: #1a1a2e;
    --text-secondary: #4a5568;
    --border-color: #e0e0e5;
    --accent-color: #0099cc;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

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

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 60px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo-text {
    font-size: 24px;
    font-weight: 700;
    background: linear-gradient(90deg, #0099cc, #00b8e6, #0099cc);
    background-size: 200% 100%;
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -0.5px;
    position: relative;
    animation: gradient-flow 3s linear infinite;
}

@keyframes gradient-flow {
    0% {
        background-position: 0% 50%;
    }
    100% {
        background-position: 200% 50%;
    }
}

.logo-text::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 100%;
    height: 2px;
    background: linear-gradient(90deg, var(--primary-color), var(--primary-light), var(--primary-color));
    background-size: 200% 100%;
    animation: gradient-flow 3s linear infinite;
}

.nav {
    display: flex;
    gap: 28px;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    font-size: 14px;
    transition: all 0.2s ease;
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 1px;
    background-color: var(--primary-color);
    transition: width 0.2s ease;
}

.nav-link:hover {
    color: var(--text-primary);
}

.nav-link:hover::after {
    width: 100%;
}

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

.mobile-menu-btn span {
    width: 22px;
    height: 2px;
    background-color: var(--text-primary);
}

.hero {
    padding: 40px 0 35px;
    text-align: center;
    position: relative;
}

.hero-title {
    font-size: 32px;
    font-weight: 700;
    margin-bottom: 12px;
    line-height: 1.3;
}

.hero-subtitle {
    font-size: 15px;
    color: var(--text-secondary);
    margin-bottom: 24px;
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}

.search-form {
    display: flex;
    max-width: 500px;
    margin: 0 auto 24px;
    background-color: var(--bg-card);
    border-radius: 8px;
    overflow: hidden;
    border: 1px solid var(--border-color);
    transition: all 0.3s ease;
}

.search-form:focus-within {
    border-color: var(--primary-color);
    box-shadow: 0 0 15px rgba(0, 153, 204, 0.15);
}

.search-input {
    flex: 1;
    padding: 10px 16px;
    background: none;
    border: none;
    outline: none;
    color: var(--text-primary);
    font-size: 14px;
}

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

.search-btn {
    padding: 10px 24px;
    background-color: var(--primary-color);
    border: none;
    cursor: pointer;
    font-size: 14px;
    color: white;
    font-weight: 600;
    transition: all 0.2s ease;
}

.search-btn:hover {
    background-color: #0080aa;
    box-shadow: 0 0 12px rgba(0, 153, 204, 0.3);
}

.stats {
    display: flex;
    justify-content: center;
    gap: 80px;
}

.stat-item {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 36px;
    font-weight: 700;
    color: var(--primary-color);
}

.stat-label {
    display: block;
    font-size: 13px;
    color: var(--text-secondary);
    margin-top: 6px;
}

.section-title {
    font-size: 26px;
    font-weight: 600;
    margin-bottom: 28px;
    text-align: center;
    position: relative;
}

.section-title::before {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 40px;
    height: 2px;
    background: linear-gradient(90deg, transparent, var(--primary-color), transparent);
}

.categories {
    padding: 35px 0 40px;
}

.category-group {
    margin-bottom: 20px;
    background-color: var(--bg-card);
    border-radius: 10px;
    border: 1px solid var(--border-color);
    overflow: hidden;
    transition: all 0.3s ease;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.03);
}

.category-group:hover {
    border-color: rgba(0, 153, 204, 0.4);
    box-shadow: 0 4px 16px rgba(0, 153, 204, 0.08), 0 2px 6px rgba(0, 0, 0, 0.05);
    transform: translateY(-1px);
}

.category-header {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 16px 20px;
    background-color: var(--bg-card);
    border-bottom: 1px solid var(--border-color);
}

.category-icon {
    font-size: 22px;
}

.category-title {
    font-weight: 600;
    font-size: 16px;
    color: var(--text-primary);
    text-decoration: none;
    transition: color 0.2s ease;
}

.category-title:hover {
    color: var(--primary-color);
}

.category-count {
    margin-left: auto;
    font-size: 12px;
    color: var(--primary-color);
    background-color: rgba(0, 153, 204, 0.1);
    padding: 4px 12px;
    border-radius: 12px;
    font-weight: 500;
}

.tool-links {
    display: flex;
    flex-wrap: wrap;
    padding: 16px 20px;
    gap: 14px;
}

.tool-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 13px;
    padding: 8px 14px;
    border-radius: 6px;
    transition: all 0.25s ease;
    background-color: rgba(0, 153, 204, 0.05);
    border: 1px solid transparent;
    position: relative;
}

.tool-links a:hover {
    color: var(--primary-color);
    background-color: rgba(0, 153, 204, 0.12);
    border-color: rgba(0, 153, 204, 0.3);
    transform: translateY(-2px);
    box-shadow: 0 2px 8px rgba(0, 153, 204, 0.15);
}

.featured {
    padding: 35px 0 40px;
    background-color: rgba(0, 153, 204, 0.03);
}

.featured-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
    gap: 14px;
}

.featured-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 20px 14px;
    background-color: #ffffff;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    text-decoration: none;
    transition: all 0.2s ease;
}

.featured-item:hover {
    background-color: var(--bg-card-hover);
    border-color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.featured-icon {
    font-size: 32px;
}

.featured-name {
    font-size: 13px;
    font-weight: 500;
    color: var(--text-primary);
}

.about {
    padding: 30px 0;
    text-align: center;
}

.about-content {
    max-width: 700px;
    margin: 0 auto;
    color: var(--text-secondary);
    font-size: 15px;
    line-height: 1.8;
}

.about-content p {
    margin-bottom: 16px;
}

.footer {
    padding: 25px 0;
    border-top: 1px solid var(--border-color);
    margin-top: 30px;
    background-color: var(--bg-card);
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
}

.footer-links {
    display: flex;
    gap: 28px;
}

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 13px;
    transition: color 0.2s ease;
}

.footer-links a:hover {
    color: var(--primary-color);
}

.footer-friend-links {
    display: flex;
    align-items: center;
    gap: 12px;
    flex-wrap: wrap;
}

.friend-links-label {
    font-size: 11px;
    color: var(--text-secondary);
    font-weight: 500;
}

.footer-friend-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 11px;
    transition: color 0.2s ease;
}

.footer-friend-links a:hover {
    color: var(--primary-color);
}

.footer-copyright {
    color: var(--text-secondary);
    font-size: 12px;
}

@media (max-width: 768px) {
    .hero-title {
        font-size: 26px;
    }
    
    .hero-subtitle {
        font-size: 14px;
    }
    
    .stats {
        gap: 30px;
    }
    
    .stat-number {
        font-size: 28px;
    }
    
    .nav {
        display: none;
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    .section-title {
        font-size: 22px;
    }
    
    .tool-links {
        gap: 10px;
    }
    
    .tool-links a {
        font-size: 12px;
        padding: 5px 10px;
    }
    
    .footer-links {
        gap: 18px;
    }
    
    .featured-grid {
        grid-template-columns: repeat(auto-fit, minmax(110px, 1fr));
        gap: 10px;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 40px 0;
    }
    
    .hero-title {
        font-size: 24px;
    }
    
    .hero-subtitle {
        font-size: 13px;
    }
    
    .stats {
        gap: 20px;
    }
    
    .stat-number {
        font-size: 22px;
    }
    
    .stat-label {
        font-size: 11px;
    }
    
    .tool-links {
        gap: 8px;
    }
    
    .tool-links a {
        font-size: 11px;
        padding: 4px 8px;
    }
    
    .featured-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 8px;
    }
    
    .featured-icon {
        font-size: 24px;
    }
    
    .featured-name {
        font-size: 11px;
    }
}