左中右布局，中间自适应并优先显示在前面

<div class="container">
  <div class="center">
    <div class="cont">中间内容</div>
  </div>
  <div class="left">左侧内容</div>
  <div class="right">右侧内容</div>
</div>
<div class="container2">
  <div class="center2">中间内容2</div>
  <div class="left2">左侧内容2</div>
  <div class="right2">右侧内容2</div>
</div>
<div class="container3">
  <div class="center3">中间内容3</div>
  <div class="left3">左边内容3</div>
  <div class="right3">右边内容3</div>
</div>
<div class="container4">
  <div class="center4">中间内容4</div>
  <div class="left4">左侧内容4</div>
  <div class="right4">右侧内容4</div>
</div>

<div class="container5">
  <div class="center5">中间内容5</div>
  <div class="left5">左侧内容5</div>
  <div class="right5">右侧内容5</div>
</div><div class="container">
  <div class="cente