.head3 {
    background: url(images/head6.png) no-repeat center center;
    width: 100%;
    height: 248px;
    padding-top: 6px;
}
.list {
    width: 990px;
    height: 249px;
   
    margin: 0 auto;
}
.list img{width: 990px;height: 249px;display: block}