Using Chrome to inspect the toolbar elements I can see that this style rule from Artisteer is causing the problem:
.art-post ul > li {
background: none;
padding-left: 0;
overflow: visible;
background-repeat: no-repeat;
}
the background:none; is overriding the css from telerik. You could edit the style.css to remove that.
Regarding the layout (ie you describe it as too large, but that isn't really the problem), it looks to me like you did not use a 3 column layout in Artisteer as indicated in the instructions therefore the exported css lacks what is needs for the left column width. I cannot reproduce that problem using a 3 column layout in Artisteer.
I would change it in Artisteer to use 3 columns then re-export then tweak the css to solve the toolbar problem.
Hope that helps,
Joe