Which version of dhtmlxGrid you are using?
In case of older grid (2.6 or below) try to reorder css files, so the first stylesheet on the page is loaded from the same domain as HTML file
Can you provide uses setStyle command? It seems that styles which you are using affect the both code of custom styling and height of the result container. The both above modifications must not cause any issues ( but I’m not sure how they fix the original problem, because result code contains the same logic, just with a bit different formatting )