How to make IMG in LI stack regardless of height

Example Site

What I am running into is that my images only stack on the right side. Now I would like to have it on both, but it seems the left side is connecting to the right side images. How can I fix the left side so it stacks like the right?

HTML snipet:

<li class="searchable" data-index="TAG"><dl>
    <dt><img src="IMAGE"></dt>
    <dt>CAPTION</dt></dl></li>

CSS Snipet:

dl{
    color: yellow;
    font-size: 30px;
    }



li {
    float: left;
    list-style-type: none;
    padding-left: 50px;
    padding-bottom:20px;
    }

img{
    width: 400px;
    background-color: rgba(144,144,144,.3);
    box-shadow: 0px 0px 15px black;
    }

~Xplo