https://www.cnblogs.com/zqzjs/archive/2017/02/10/6380318.html
.price-monitoring-list-left img {
display: block;
position: relative;
text-align: center;
}
.price-monitoring-list-left img:after {
content: url(src/assets/img/default.png);
display: block;
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
background-color: #fff;
}