JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.3.1/css/bootstrap-combined.min.css">
<div class="row">
		<div class="span6">
			<a href="#" class="thumbnail">
				<div class="frontpage_square">
					<img src="" class="img img-responsive full-width" />
				</div>
			</a>
       </div>
	  <div class="span6">
	<div class="row">	   
        <div class="span2">
			<a href="#" class="thumbnail">
				<div class="frontpage_square">
					<img src="" class="img img-responsive full-width" />
				</div>
			</a>
       </div>
	   <div class="span2">
			<a href="#" class="thumbnail">
				<div class="frontpage_square">
					<img src="" class="img img-responsive full-width" />
				</div>
			</a>
       </div>
	   <div class="span2">
			<a href="#" class="thumbnail">
				<div class="frontpage_square">
					<img src="" class="img img-responsive full-width" />
				</div>
			</a>
       </div>  
      </div>
	  <div class="row">	   
        <div class="span2">
			<a href="#" class="thumbnail">
				<div class="frontpage_square">
					<img src="" class="img img-responsive full-width" />
				</div>
			</a>
       </div>
	   <div class="span2">
			<a href="#" class="thumbnail">
				<div class="frontpage_square">
					<img src="" class="img img-responsive full-width" />
				</div>
			</a>
       </div>
	   <div class="span2">
			<a href="#" class="thumbnail">
				<div class="frontpage_square">
					<img src="" class="img img-responsive full-width" />
				</div>
			</a>
       </div>  
      </div>
	  <div class="row">	   
        <div class="span2">
			<a href="#" class="thumbnail">
				<div class="frontpage_square">
					<img src="" class="img img-responsive full-width" />
				</div>
			</a>
       </div>
	   <div class="span2">
			<a href="#" class="thumbnail">
				<div class="frontpage_square">
					<img src="" class="img img-responsive full-width" />
				</div>
			</a>
       </div>
	   <div class="span2">
			<a href="#" class="thumbnail">
				<div...

CSS

.frontpage_square{
    position:relative;
    overflow:hidden;
    padding-bottom:100%;
}
.frontpage_square img{
    position:absolute;
}