.filter_box {
    height: 35px;
    width: 100%;
    background-color: #E2E2E4;
    margin-top: 5px;
    clear: both;
    position: relative;;
}

.filter_item {
    display: block;
    height: 34px;
    width: auto;
    line-height: 34px;
    text-align: center;
    color: #999999;
    font-size: 14px;
    margin-left: 30px;
    cursor: pointer;
    float: left;
}

.filter_item.active {
    color: #177DFF;
}


.course_list_box {
    margin-top: 20px;
    margin-left: 0;
    margin-right: 0;
}

.course_item {
    /*width: 25%;*/
    /*width: 33.333%;*/
    width: 281px;
    margin-left: 33px;
    padding: 0px;
    box-sizing: border-box;
    margin-bottom: 20px;
    border-radius: 0;
}
.course_item:nth-child(3n+1) {
    margin-left: 0;
}

.course_item_inner {
    /*border-radius: 8px;*/
    overflow-y: hidden;
    background: #fff;
    width: 100%;
    /*height: 246px;*/
    height: 270px;
    transition: all ease 0.3s;
    /*overflow: hidden;*/

}

.course_item_inner:hover {
    transform: translateY(-5px);

    box-shadow: 0 9px 28px 6px hsl(0deg 0% 60% / 5%), 0 6px 16px 0 hsl(0deg 0% 60% / 8%), 0 3px 6px -4px hsl(0deg 0% 60% / 12%);
}

.course_item_inner:hover .mask {
    opacity: 1;
}

.course_item_inner:hover .title {
    color: #177DFF;
}

.cover_box {
    width: 100%;
    height: 160px;
    position: relative;
}


.cover_box img {
    display: block;
    object-fit: cover;
    width: 100%;
    height: 100%;
}

.cover_box .mask {
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    position: absolute;
    background: transparent;
    /*opacity: 0;*/
    transition: all .3s ease-in-out;
}

.cover_box .lesson_info {
    position: absolute;
    font-size: 14px;
    color: #fff;
    height: 30px;
    background-color: #177DFF;
    right: 10px;
    bottom: 0;
    line-height: 30px;
    text-indent:0;width: auto; min-width: 90px;
    padding-left: 37px;
    background-image: url(../image/icon-course.png);
    background-size: 22px 20px;
    background-repeat: no-repeat;
    background-position:  9px center;
}


.course_item_bottom {

}

.course_item_bottom .title {
    width: 100%;
    box-sizing: border-box;
    padding: 19px 16px 0;
    line-height: 1;
    font-size: 16px;
    font-weight: bold;
    color: #111;
    overflow: hidden;
    text-overflow: ellipsis;
    word-break: break-all;
    white-space: nowrap;
    transition: color ease 0.3s;
}

.course_item_bottom .mode {
    padding: 12px 16px 15px;
    line-height: 1;
    color: #999;
}

.course_item_bottom .price {
    display: flex;
    box-sizing: border-box;
    padding: 0px 16px 0;
    justify-content: space-between;
    align-items: center;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    color: #CE001E;
    line-height: 1;

}

.mask a.cancel {
    display: inline-block;
    margin: 10px 0;
    width: 65px;
    text-align: center;
    line-height: 23px;
    color: #fff;
    font-size: 12px;
    background: rgba(0, 0, 0, 0.5);
}