.lbt1 {
    /* margin: 200px auto 0; */
    width: 1350px;
    overflow: hidden;
    position: relative;
}

.large_box {
    margin-bottom: 10px;
    width: 100%;
    height: 760px;
    overflow: hidden;
    z-index: -1;
}

.large_box img {
    display: block;
}

.small_box {
    width: 580px;
    height: 135px;
    overflow: hidden;
    position: absolute;
    top: 500px;
    right: 55px;
}

.small_list {
    position: relative;
    float: left;
    width: 520px;
    height: 135px;
    overflow: hidden;
}

.small_list ul {
    height: 135px;
    overflow: hidden;
}

.small_list ul li {
    position: relative;
    float: left;
    margin-right: 10px;
    width: 245px;
    /* filter: grayscale(1); */
}


/* 灰色盒子 */

.small_list ul li {
    filter: grayscale(100%);
    -webkit-filter: grayscale(100%);
    -moz-filter: grayscale(100%);
    -ms-filter: grayscale(100%);
    -o-filter: grayscale(100%);
    filter: progid: DXImageTransform.Microsoft.BasicImage(grayscale=1);
    -webkit-filter: grayscale(1);
}

.small_list ul li img {
    display: block;
}

.small_list ul li .bun_bg {
    display: none;
    position: absolute;
    top: 0;
    left: 0;
    width: 245px;
    height: 135px;
    background: #000;
    filter: alpha(opacity=60);
    -moz-opacity: 0.6;
    -khtml-opacity: 0.6;
    opacity: 0.6;
}

.small_list ul li.on .bun_bg {
    display: block;
}

.btn {
    display: block;
    width: 43px;
    height: 43px;
    background-color: #777;
    background-repeat: no-repeat;
    background-position: center center;
    cursor: pointer;
}

.btn:hover {
    background-color: #e7000e;
}

.left_btn {
    margin-top: 25px;
    margin-bottom: 10px;
}

.large_box ul li {
    position: relative;
}

.large_box ul li a img {
    width: 1350px;
    height: 760px;
}

.large_box ul li span {
    position: absolute;
    left: 88px;
    top: 520px;
    width: 510px;
    height: 145px;
    color: #fff;
}

.large_box ul li span h3 {
    font-size: 18px;
    font-weight: 600;
}

.large_box ul li span p {
    margin-top: 10px;
    font-size: 15px;
}

.on {
    display: none;
}