.mainStyle {
    width: 930px;
    padding: 40px 0;
    /*border:dotted 2px red;*/
    position: relative;
    text-align: center;
    float: left;
    margin-left:15px;
    margin-top:15px;
}

    .mainStyle ul {
        width: 100%;
    }

        .mainStyle ul li {
            width: 242px;
            height: 159px;
            border: 3px solid #ddd;
            float: left;
            margin-right: 23px;
            margin-bottom: 13px;
        }

            .mainStyle ul li img {
                padding-top: 10px;
                width: 232px;
                height: 153px;
                vertical-align: top;
                display: inline-block;
            }