This is a where the Fire Bug add on fire fox is very usefull, it allows you to select elements on the page to see what CSS is being applied to the particular element.
in your caase, the problem is that the height of the image div is set to 200px.
in the webassist/themes/Ambience/css/default_styles.css
change:
.gridBox .imageWrapper {
height: 200px;
overflow: hidden;
padding: 6px;
text-align: center;
}
to:
.gridBox .imageWrapper {
height: 150px;
overflow: hidden;
padding: 6px;
text-align: center;
}