Block Grid Advanced

<ul class="small-block-grid-2 medium-block-grid-3 large-block-grid-4">
    <li><img src="http://placekitten.com/600/400"></li>
    <li><img src="http://placekitten.com/600/400"></li>
    <li><img src="http://placekitten.com/600/400"></li>
    <li><img src="http://placekitten.com/600/400"></li>
    <li><img src="http://placekitten.com/600/400"></li>
    <li><img src="http://placekitten.com/600/400"></li>
</ul>