css实现图片按宽等比例缩放不变形

  

    
  


#evalPage .imgbox{
  width: 20%;
  height:0; //容器内有内容，所以要将height设为0
  padding-bottom: 20%; //这里和宽值一样
  overflow: hidden;
  position: relative;
}
#evalPage .imgbox .image__inner{
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  width: 100%;
  height: 100%;
}