左边固定右边自适应

```js
 .box {
 height: 500px;
 display: flex;
 }
 .box div {
 height: 300px;
 text-align: center;
 }
 .box div.right {
 flex: 1;//右边自适应
 border: 1px solid #000000;
 }
 .box div.left {
 border: 1px solid #000000;
 flex-basis: 100px;//左边固定,优先级最高
 }
 //html
 <div class="box">
 <div class="left">左边固定效果</div>
 <div class="right">右边自适应效果</div>
 </div>
```