There is a width of 300px added that should either be removed or adjusted –
.home-feature-bg-alt .featuredpage .page,
.home-feature-bg-alt .featuredpost .post {
float: left;
margin: 0;
overflow: hidden;
padding: 0 0 5px;
width: 300px;
}
This can be found on line 1403 in your style.css file.