.banner {
    width: 100%;
    min-width: 1200px;
    height: 264px;
    background: url(https://www.f139content.com/website/sci99/images/banner.png) top center no-repeat;
}

.div_main {
    background: #fff;
    width: 1200px;
    min-height: 500px;
    margin: 0 auto;
    padding: 32px 0 57px 0;
}

.leftnav {
    width: 112px;
    float: left;
}

.vertical-divider {
    height: 350px;
    width: 2px;
    background-color: #CFD1D8;
    float: left;
}

.leftnav a {
    display: block;
    width: 56px;
    height: 24px;
    margin-bottom: 20px;
    cursor: pointer;
    font-size: 14px;
    color: #666666;
    font-family: SourceHanSansCN, sans-serif;
}

.leftnav a:hover {
    color: #2050D1;
    font-weight: 700;
    border-bottom: 2px solid #2050D1;
}

.leftnav a.active {
    color: #2050D1;
    font-weight: 700;
    border-bottom: 2px solid #2050D1;
}

.content {
    width: 1038px;
    float: right;
    display: none;
}

.content.active {
    display: block;
}

.clearfix:after {
    visibility: hidden;
    display: block;
    font-size: 0;
    content: " ";
    clear: both;
    height: 0;
}

.content .item {
    margin: 0 24px 24px 0;
    width: 330px;
    float: left;
}

.content .item:nth-child(3n) {
    margin-right: 0;
}

.content .item:nth-child(3n+1){
    clear: left
}

.content .item .img-box {
    position: relative;
    width: 330px;
    height: 192px;
    cursor: pointer;
}

.content .item .img-box img {
    width: 100%;
    height: 100%;
}

.content .item .img-box .overlay {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 330px;
    height: 67px;
    background: linear-gradient( 180deg, rgba(255,255,255,0) 0%, #FFFFFF 100%);
}

.content .item .img-box .tag {
    position: absolute;
    z-index: 10;
    bottom: 0;
    right: 0;
    padding: 2px 5px;
    background: rgba(32, 80, 209, 0.09);
    border-radius: 4px 0 0 0;
    font-family: SourceHanSansCN, sans-serif;
    font-size: 10px;
    color: #2050D1;
    line-height: 15px;
}

.content .item .text-box .title {
    font-family: SourceHanSansCN, sans-serif;
    font-weight: 500;
    font-size: 16px;
    line-height: 24px;
    color: #000000;
    margin: 8px 0 4px 0;
    cursor: pointer;
}

.content .item .text-box .title:hover {
    color: #2050D1;
}

.content .item .text-box p {
    text-align: justify;
    color: #666666;
    font-size: 12px;
    font-family: SourceHanSansCN, sans-serif;
    line-height: 18px;
}

/* 弹窗样式 */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.4);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.modal.active {
    display: flex;
    opacity: 1;
}

.modal-content {
    position: relative;
    max-width: 90%;
    max-height: 90%;
    background: white;
    animation: scaleUp 0.4s ease;
}

@keyframes scaleUp {
    from { transform: scale(0.8); opacity: 0; }
    to { transform: scale(1); opacity: 1; }
}

.modal-img {
    display: block;
    width: 886px;
    height: 514px;
    margin: 0 auto;
}

.close-btn {
    position: absolute;
    bottom: -48px;
    right: calc(50% - 16px);
    width: 32px;
    height: 32px;
    cursor: pointer;
    z-index: 10;
}