.brief_img_cont{
    margin: 0 -10px;
}
.brief_img_cont .brief_img{
    width: 50%;
    float: left;
}
.brief_img_cont1 .brief_img{
    width: 33.3%;
}
.brief_img_cont .brief_img .con{
    margin: 0 10px 20px;
    height: 0;
    overflow: hidden;
    padding-bottom: 54%;
}