<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<div class="container">
<h1>Choose your favourite group</h1>
<div class="cardList">
<div class="card">
<div class="card__bg" style="background-image: url('http://lorempixel.com/245/145/animals')"></div>
</div>
<div class="card">
<div class="card__bg" style="background-image: url('http://lorempixel.com/245/146/animals')"></div>
</div>
<div class="card">
<div class="card__bg" style="background-image: url('http://lorempixel.com/245/140/animals')"></div>
</div><span class="cardList__title">Group 1</span>
</div>
<div class="cardList">
<div class="card">
<div class="card__bg" style="background-image: url('http://lorempixel.com/245/146/animals')"></div>
</div>
<div class="card">
<div class="card__bg" style="background-image: url('http://lorempixel.com/245/147/animals')"></div>
</div>
<div class="card">
<div class="card__bg" style="background-image: url('http://lorempixel.com/245/141/animals')"></div>
</div><span class="cardList__title">Group 2</span>
</div>
<div class="cardList">
<div class="card">
<div class="card__bg" style="background-image: url('http://lorempixel.com/245/147/animals')"></div>
</div>
<div class="card">
<div class="card__bg" style="background-image: url('http://lorempixel.com/245/148/animals')"></div>
</div>