图片加载失败样式美化

图片加载失败的样式是比较丑的

<img src="http://img.png" alt="加载失败">

可以通过添加css美化样式

img{
  display: inline-block;
  width: 100px;
  height: 56px;
  cursor: pointer;
  position: relative;
}
img:after{
  position:absolute;
  width:100px;
  height: 56px;
  content:"" attr(alt);
  display: flex;
  justify-content: center;
  align-items: center;
  top:0;
  left:0;
  background: #eee;
  background-size:100%;
}