三层嵌套

    #center{
            height: 44px;
            background: url(img/center.jpg) 0 0  repeat-x;
        }
        #left{
            height: 44px;
            background: url(img/left.jpg) left 0 no-repeat;
        }
        #right{
            height: 44px;
            background: url(img/right.jpg) right 0 no-repeat;
        }
    <div id="center">
          <div id="left">
              <div id="right"></div>
          </div>
      </div>

2.自适应

    #con{
             400px;
            background: url(img/point.png) 0 0  repeat-x;
            height: 20px;
            overflow: hidden;
        }
        #con .left{
            float: left;
            background: #fff;
        }
        #con .right{
            float: right;
            background: #fff;
        }
<div id="con">
        <span class="left">我是一个粉刷匠</span>
        <span class="right">粉刷本领强</span>
    </div>
原文地址:https://www.cnblogs.com/SunShineM/p/6059371.html