bootstrap怎么实现自适应高度

var iScale = 1;
iScale = iScale / window.devicePixelRatio;  
document.write(&#39;<meta name="viewport" content="width=device-width,user-scalable=no,initial-scale=&#39; + iScale + &#39;,minimum-scale=&#39; + iScale + &#39;,maximum-scale=&#39; + iScale + &#39;">&#39;) 
var iWidth = document.documentElement.clientWidth;
document.getElementsByTagName(&#39;html&#39;)[0].style.fontSize = iWidth / 16 + &#39;px&#39;;

@s:46.875rem;
@color:~"div[class^='col']";
@{color}{
    background: #999;
    height: 200/@s;
  }