.yk-img{
    /*width: 1200px;*/
}
.yk-img li {
    transition: all .5s ease 0s;
    padding-bottom: 10px;
    float: left;
    width: 23.5%;
    /*margin-right: 2%;*/
    text-align: center;
    box-shadow: 0 0 3px #e6e6e6;
    margin-bottom: 30px;
}
.yk-img img {
    width: 96%;
    height: 370px;
    margin: 2%;
    max-width: 280px;
}