1.使用flex布局
<style>#back{border: red solid 1px;width: 800px;height: 500px;display: flex;align-items: center;}#left{border: blue 1px solid;width: 100px;height: 100px;justify-content: flex-start;}#right{border: blue 1px solid;width: 100px;height: 100px;justify-content: flex-end;flex:1;display: flex;}</style></head><body><div id="back"><div id="left">left</div><div id="right">right</div></div>