/* 主容器 */
.footer-container {
    width: 100%;
    height: 425px;
    background-color: #2a2a2a;
    color: #ccc;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    position: relative;
}

/* --- 页脚主体部分 --- */
.footer-main {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    /* 修改：增加左右内边距，使内容更宽 */
    padding: 50px 100px;
    flex-grow: 1;
}

.footer-logo img {
    height: 50px;
    display: block;
}

.footer-links {
    display: flex;
    /* 修改：增加列与列之间的间距 */
    gap: 80px;
}

.link-column h4 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 25px; /* 稍微增加标题下方间距 */
    color: #fff;
}

.link-column ul {
    list-style: none;
}

.link-column li {
    margin-bottom: 12px; /* 增加列表项间距 */
}

.link-column a {
    text-decoration: none;
    color: #999;
    font-size: 14px;
    transition: color 0.3s ease;
}

    .link-column a:hover {
        color: #fff;
    }

.footer-contact {
    text-align: right;
    min-width: 200px; /* 确保右侧区域有一定宽度 */
}

.contact-phone {
    font-size: 24px;
    font-weight: 700;
    color: #fff;
    margin-bottom: 25px;
    display: block;
}

.social-icons {
    display: flex;
    /* 修改：增加社交图标间距 */
    gap: 25px;
    margin-bottom: 35px;
}

.social-icon {
    width: 40px;
    height: 40px;
    background-color: #444;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color 0.3s ease, transform 0.3s ease;
    flex-shrink: 0; /* 防止图标被压缩 */
}

    .social-icon:hover {
        background-color: #666;
        transform: translateY(-2px);
    }

    .social-icon svg {
        width: 20px;
        height: 20px;
        fill: #fff;
    }

.contact-btn {
    padding: 12px 35px; /* 按钮稍微大一点 */
    background-color: transparent;
    border: 1px solid #ccc;
    border-radius: 25px;
    color: #fff;
    font-size: 14px;
    cursor: pointer;
    transition: all 0.3s ease;
    white-space: nowrap;
}

    .contact-btn:hover {
        background-color: #fff;
        color: #2a2a2a;
    }

/* --- 页脚底部部分 --- */
.footer-bottom {
    background-color: #222;
    /* 修改：增加左右内边距 */
    padding: 25px 100px;
    text-align: center;
    font-size: 12px;
    color: #888;
}

.friend-links {
    margin-bottom: 15px;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
    gap: 15px; /* 友情链接文字和图片的间距 */
}

    .friend-links span {
        margin-right: 5px;
    }

    .friend-links img {
        height: 20px;
        filter: brightness(0) invert(0.7); /* 使友情链接 logo 变灰 */
        opacity: 0.8;
        transition: opacity 0.3s;
    }

        .friend-links img:hover {
            opacity: 1;
        }

.copyright {
    margin-top: 10px;
    letter-spacing: 0.5px;
}

/* --- 返回顶部按钮 --- */
.back-to-top {
    position: absolute;
    bottom: 90px; /* 稍微向上提一点，避免和底部太近 */
    /* 修改：右侧位置随主容器内边距调整 */
    right: 100px;
    width: 40px;
    height: 40px;
    background-color: #444;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.3s ease;
    z-index: 10;
}

    .back-to-top:hover {
        background-color: #666;
        transform: translateY(-3px);
    }

    .back-to-top svg {
        width: 20px;
        height: 20px;
        fill: #fff;
    }

/* --- 响应式设计 (兼容手机模式) --- */
@media (max-width: 900px) {
    .footer-container {
        height: auto; /* 在手机上高度自适应 */
    }

    .footer-main {
        flex-direction: column;
        /* 手机端内边距适中 */
        padding: 40px 20px;
        gap: 40px;
    }

    .footer-links {
        flex-direction: column;
        /* 手机端列间距改为行间距 */
        gap: 30px;
        width: 100%;
    }

    /* 手机端可以将多列分为两列或单列，这里保持单列清晰 */
    .footer-links {
        display: grid;
        grid-template-columns: repeat(2, 1fr); /* 平板显示两列 */
        gap: 30px 20px;
    }

    .footer-contact {
        text-align: left;
        width: 100%;
        margin-top: 20px;
        border-top: 1px solid #444;
        padding-top: 30px;
    }

    .social-icons {
        justify-content: flex-start;
    }

    .contact-btn {
        width: 100%;
        max-width: 300px;
    }

    .footer-bottom {
        padding: 25px 20px;
    }

    .friend-links {
        flex-direction: column;
        gap: 10px;
    }

    .back-to-top {
        bottom: 30px;
        right: 20px;
    }
}

/* 超小屏幕手机单列显示 */
@media (max-width: 480px) {
    .footer-links {
        grid-template-columns: 1fr;
    }
}