.cont{
   width: 871px;
   margin: 90px auto 0; 
}
.cont li{
    position: relative;
    float: left;
    width: 418px;
    height: 260px;
    margin-bottom: 35px;
}
.cont li:nth-child(even){
    margin-left: 35px;
}
.cont li a{
    display: block;
}
.cont li img{
    width: 100%;
    height: 100%;
}
.cont li .tit{
    position: absolute;
    left: 50%;
    top: 50%;
    margin-left: -95px;
    margin-top: -25px;
    display: block;
    width: 152px;
    height: 50px;
    line-height: 50px;
    background: url('../images/set.png')no-repeat center;
    padding-left: 38px;
    color: #fff;
    font-size: 20px;
}
.mask{
    display: none;
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(12,126,217,.8);
    overflow: hidden;
}
.mask h6{
    font-size: 20px;
    color: #fff;
    margin-top: 27px;
    text-align: center;
}
.mask p{
    font-size: 14px;
    color: #fff;
    line-height: 26px;
    width: 335px;
    margin: 10px auto 0;
    text-align: justify;
}