给父盒子加相对定位
.rater-main .rater-img2{
width: 266px;
height: 196px;
overflow: hidden;
background-color: #fff;
position: relative;
}
给子元素绝对定位
.rater-main > li img{
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
margin: auto;
max-width: 100%;
max-height: 100%;
}