It looks like there is an issue somewhere in the custom css that you added. You can add a minimum height to temporarily fix it around line 1530 like this –
.featuredpage .page,
.featuredpost .post {
float: left;
min-height: 350px;
margin: 0;
overflow: hidden;
padding: 0 0 5px;
}
You can adjust it more if you want more space, but that should fix it.