.container{
  width: 400px;
  height: 300px;
  border: 1px solid red;
  background:url(https://gitee.com/SCD-Wear/img-bed/raw/master/css/panda.jpg);
  background-size: contain;
  background-repeat: no-repeat;
  background-position: center center;

/*   background-size: cover; */
}