.header{
    background: #0C0C0F;
}
.course_tab{
    width: 1200px;
    margin: 0 auto;
    padding-top: 120px;
    display: flex;
    border-bottom: 2px solid #eeeeee;
    font-size: 16px;
}
.course_tab a{
    margin-right: 40px;
    padding-bottom: 20px;
    color: #999999;
    padding-left: 10px;
    padding-right: 10px;
}
.course_tab a:hover,.course_tab a.active{
    color: #111111;
    border-bottom: 6px solid #FE7159;
}
.course_list{
    width: 1200px;
    margin: 0 auto;
    display: flex;
    flex-direction: row;
    flex-wrap: wrap;
}
.course_list .item{
    margin-top: 20px;
    margin-right: 20px;
    width: 590px;
    height: 230px;
    position: relative;
}
.course_list .item:nth-child(2n){
    margin-right: 0;
}
.course_list .item img{
    border-radius: 10px;
}

.course_list .item .overlay{
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    position: absolute;
    display: flex;
    flex-direction: column;
}
.course_list .item .overlay .tags{
    width: 110px;
    height: 30px;
    text-align: center;
    background-color: #FE7159;
    border-radius: 10px 0px;
    line-height: 30px;
    color: #eeeeee;
}
.course_list .item .overlay .title{
    font-size: 32px;
    color: #ffffff;
    height: 36px;
    margin-top: 19px;
    margin-left: 30px;
}
.course_list .item .overlay .cont{
    margin-top: 15px;
    margin-left: 30px;
    display: flex;
    flex: 1;
}
.course_list .item .overlay .cont .biaoqian{
    flex: 1;
}
.course_list .item .overlay .cont .bq{
    flex: 1;
    display: inline-block;
    width: 70px;
    height: 26px;
    background: rgba(255,255,255,0.3);
    border-radius: 3px;
    color: #ffffff;
    font-size: 12px;
    line-height: 26px;
    text-align: center;
    margin-right: 10px;
}
.course_list .item .overlay .cont .btn{
    width:84px;
    height: 30px;
    line-height: 30px;
    text-align: center;
    color: #ffffff;
    background-color: #FF7361;
    margin-right: 30px;
    border-radius: 6px;
}
.course_list .item .overlay .desc{
    background: #000000;
    border-radius: 0px 0px 10px 10px;
    opacity: 0.7;
    width: 100%;
    height: 90px;
    z-index: 9999;
    color: #eeeeee;
    padding: 20px 30px;
    box-sizing: border-box;
    line-height: 1.35;
}
.course_detail{
    width: 1200px;
    margin-left: auto;
    margin-right: auto;
    margin-top: 20px;
    background-color: #fff;
    border-radius: 10px;
    padding: 5rem;
    box-sizing: border-box;
    text-align: center;
}
.course_detail .empty{
    margin-top: 20px;
    color: #999999;
}