如何让图片完全按比例显示在@media屏幕上？

.container {
  width: 100%;
  height: 300px;
}

.container {
  background-image: url("图片链接");
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
}

@media screen and (max-width: 768px) {
  .container {
    height: 200px;
  }
}

@media screen and (max-width: 480px) {
  .container {
    height: 150px;
  }
}