/* 幻灯片容器 */
#banner_main {
    width: 100%;
    overflow: hidden;
    background: #f5f5f5;
}

#banner {
    width: 100%;
    max-width: 1920px;
    margin: 0 auto;
    position: relative;
    height: 550px; /* 固定高度 */
}

/* 幻灯片列表 */
#banner .list {
    width: 100%;
    height: 100%;
    position: relative;
}

#banner .list li {
    position: absolute;
    width: 100%;
    height: 100%;
    left: 0;
    top: 0;
    opacity: 0;
    z-index: 1;
    transition: opacity 1s ease;
}

#banner .list li:first-child {
    opacity: 1;
    z-index: 2;
}

/* 图片样式 */
#banner .list li img {
    width: 100%;
    height: 100%;
    object-fit: cover; /* 保持图片比例并覆盖容器 */
    object-position: center center; /* 图片居中 */
}

/* 导航按钮 */
#banner .tip {
    position: absolute;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    z-index: 10;
}

#banner .tip span {
    display: inline-block;
    width: 12px;
    height: 12px;
    margin: 0 5px;
    border-radius: 50%;
    background: rgba(255,255,255,0.5);
    cursor: pointer;
}

#banner .tip span.on {
    background: #fff;
}

#btn_prev, #btn_next {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 40px;
    height: 60px;
    background: rgba(0,0,0,0.3);
    z-index: 10;
    color: #fff;
    text-align: center;
    line-height: 60px;
    font-size: 24px;
    cursor: pointer;
}

#btn_prev {
    left: 20px;
}

#btn_next {
    right: 20px;
}