:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --light-bg: #f8f9fa;
    --dark-bg: #2c3e50;
    --text-color: #333;
    --light-text: #fff;
}

body {
    font-family: "PingFang SC", "Microsoft YaHei", sans-serif;
    color: var(--text-color);
    line-height: 1.6;
}

/* Header Styles */
.navbar {
    background: linear-gradient(to right, var(--primary-color), var(--secondary-color));
    padding: 1rem 0;
}

.navbar-brand img {
    max-height: 40px;
}

.nav-link {
    color: var(--light-text) !important;
    font-weight: 500;
    padding: 0.5rem 1rem;
    transition: all 0.3s ease;
}

.nav-link:hover {
    color: rgba(255, 255, 255, 0.8) !important;
    transform: translateY(-2px);
}

/* Footer Styles */
.footer {
    background: var(--dark-bg);
    color: var(--light-text);
    padding: 4rem 0 2rem;
}

.footer h5 {
    color: var(--secondary-color);
    margin-bottom: 1.5rem;
}

.footer-links span {
    display: inline-block;
    margin: 0.5rem 1rem 0.5rem 0;
    cursor: pointer;
    transition: color 0.3s ease;
}

.footer-links span:hover {
    color: var(--secondary-color);
}

.service-promise i {
    color: var(--secondary-color);
    margin-right: 0.5rem;
}

.footer-bottom {
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    text-align: center;
    font-size: 0.9rem;
}

/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    background: var(--secondary-color);
    color: var(--light-text);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s ease;
    opacity: 0;
    visibility: hidden;
}

.back-to-top.show {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background: var(--primary-color);
    transform: translateY(-3px);
}

/* Responsive Design */
@media (max-width: 768px) {
    .navbar-nav {
        background: var(--primary-color);
        padding: 1rem;
        border-radius: 0.5rem;
    }
    
    .footer {
        text-align: center;
    }
    
    .footer-links {
        margin-top: 2rem;
    }
}