I use Chrome all the time and this does not happen on my sites.
The only thing I can think of that might cause that is if you are using a version of mojoPortal where you modified the source code,especially something in the /App_Browsers/CSSFriendlyAdapters.browser file which controls how rendering is done based on the browser type. This problem is not reproducable using the official mojoPortal release packages nor using the official source code.
Note that changes in those .browser files require rebuilding the source code.
Hope that helps,
Joe