左边宽度固定，右边宽度自适应的三种写法

<div class=‘demo‘>
        <div class="left">left</div>
        <div class="right">right</div>
    </div>

 .left {
        width: 200px;
        background-color: red;
    }

    .right {
        width: 100%;
        height: 200px;
        background-color: blue;
    }

 .demo{
        display: flex;
    }
    .demo .right{
        flex:1;
    }

.demo{
        overflow: hidden;
        
    }
    .demo .left{
        float: left;
    }

.demo{
        overflow: hidden;
    }
    .demo .left{
        float: left;
    }
    .demo .right{
      float: left;
      width: calc(100% - 200px);
    }