/* ============================================================
   公共底部样式 — 用于首页、新闻页及其他需要统一底部的页面
   ============================================================ */

.footer {
    background: var(--dark);
    color: rgba(255,255,255,0.7);
    padding: 60px 0 30px;
}
.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 40px;
}
.footer-brand h3 {
    color: var(--white);
    font-size: 22px;
    font-weight: 700;
    margin-bottom: 14px;
}
.footer-brand p {
    font-size: 13px;
    line-height: 1.8;
    margin-bottom: 16px;
}
.footer-brand .footer-contact p {
    margin-bottom: 8px;
    font-size: 13px;
}
.footer-brand .footer-contact i {
    margin-right: 8px;
    color: var(--primary);
}
.footer-col h4 {
    color: var(--white);
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 18px;
    position: relative;
    padding-bottom: 10px;
}
.footer-col h4::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 30px;
    height: 2px;
    background: var(--primary);
    border-radius: 1px;
}
.footer-col a {
    display: block;
    font-size: 13px;
    color: rgba(255,255,255,0.6);
    padding: 5px 0;
    transition: all 0.2s;
    text-decoration: none;
}
.footer-col a:hover {
    color: var(--primary);
    padding-left: 4px;
}
.footer-bottom {
    border-top: 1px solid rgba(255,255,255,0.1);
    padding-top: 24px;
    text-align: center;
    font-size: 13px;
    color: rgba(255,255,255,0.4);
}

/* ========== 回到顶部 ========== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 44px;
    height: 44px;
    background: var(--primary);
    color: var(--white);
    border: none;
    border-radius: 50%;
    font-size: 20px;
    cursor: pointer;
    box-shadow: var(--shadow);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s;
    z-index: 999;
    display: flex;
    align-items: center;
    justify-content: center;
}
.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}
.back-to-top:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
}

/* ========== 响应式 ========== */
@media (max-width: 1024px) {
    .footer-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 768px) {
    .footer { padding: 40px 0 24px; }
    .footer-grid { grid-template-columns: 1fr; gap: 30px; margin-bottom: 30px; }
    .footer-brand p { margin-bottom: 12px; }
    .back-to-top {
        bottom: 20px;
        right: 20px;
        width: 40px;
        height: 40px;
        font-size: 18px;
    }
}