<div class="positionleft">我是position方式的左边，占30%</div>
        <div class="positionright">我是position方式的右边，占70%</div>

 .positionleft {
           position: relative;
           display: inline-block;
           background-color: #8d8d8d;
           width: 30%;
           height: 20%;

       }
       .positionright {
           position: relative;
           display: inline-block;
           left: 0;
           background-color: #ff8888;
           width: 70%;
           height: 20%;
       }

<div class="positionleft">我是position方式的左边，占30%</div> <div class="positionright">我是position方式的右边，占70%
</div>