/**
 * 清远市制造业赋能服务平台 - 底部导航栏样式
 * 从 main.css 抽离，便于统一维护
 * 
 * 包含：底部footer样式、返回顶部按钮、响应式适配
 */

/* ========================================
   底部
   ======================================== */
.footer {
    background: linear-gradient(180deg, var(--text-primary) 0%, #111827 100%);
    color: white;
}

.footer-main {
    padding: var(--spacing-3xl) 0;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr 1fr;
    gap: var(--spacing-xl);
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.footer-logo .logo-icon {
    width: 32px;
    height: 32px;
    color: white;
}

.footer-logo span {
    font-size: var(--font-size-base);
    font-weight: 600;
}

.footer-desc {
    font-size: var(--font-size-sm);
    color: rgba(255, 255, 255, 0.7);
    line-height: 1.6;
    margin-bottom: var(--spacing-lg);
}

.footer-contact {
    font-size: var(--font-size-sm);
    color: rgba(255, 255, 255, 0.8);
    line-height: 1.8;
}

.footer-contact strong {
    color: white;
}

.footer-links h4 {
    font-size: var(--font-size-base);
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    color: white;
}

.footer-links ul {
    list-style: none;
}

.footer-links li {
    margin-bottom: var(--spacing-sm);
}

.footer-links a {
    font-size: var(--font-size-sm);
    color: rgba(255, 255, 255, 0.7);
    transition: all var(--transition-fast);
}

.footer-links a:hover {
    color: white;
    padding-left: var(--spacing-xs);
}

.footer-qrcode h4 {
    font-size: var(--font-size-base);
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    color: white;
}

.qrcode-placeholder {
    width: 120px;
    height: 120px;
    background: white;
    border-radius: var(--radius-lg);
    overflow: hidden;
    margin-bottom: var(--spacing-sm);
}

.qrcode-placeholder img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.footer-qrcode p {
    font-size: var(--font-size-xs);
    color: rgba(255, 255, 255, 0.6);
}

.footer-bottom {
    padding: var(--spacing-lg) 0;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-bottom p {
    font-size: var(--font-size-sm);
    color: rgba(255, 255, 255, 0.6);
    text-align: center;
}

.footer-bottom a {
    color: rgba(255, 255, 255, 0.6);
    transition: color var(--transition-fast);
}

.footer-bottom a:hover {
    color: white;
}

/* ========================================
   返回顶部
   ======================================== */
.back-to-top {
    position: fixed;
    bottom: var(--spacing-xl);
    right: var(--spacing-xl);
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--gradient-primary);
    color: white;
    border-radius: 50%;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all var(--transition-normal);
    z-index: var(--z-sticky);
    cursor: pointer;
    border: none;
}

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

.back-to-top:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.back-to-top svg {
    width: 24px;
    height: 24px;
}

/* ========================================
   底部响应式适配
   ======================================== */

/* 1200px */
@media (max-width: 1200px) {
    .footer-grid {
        grid-template-columns: 2fr 1fr 1fr;
    }
    
    .footer-links:nth-child(4),
    .footer-qrcode {
        display: none;
    }
}

/* 768px */
@media (max-width: 768px) {
    .footer-grid {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .footer-logo {
        justify-content: center;
    }
}

/* 576px */
@media (max-width: 576px) {
    .footer-main {
        display: none;
    }

    .footer-grid {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .footer-logo {
        justify-content: center;
    }

    .footer-logo .logo-img {
        height: 32px;
    }
}