To grgsr, we have a How To document on using CSS Menu Writer to create new layouts for SiteAssist. You can use the menu that you create in Menu Writer in combination with a template or a CSS Sculptor preset to generate your new SiteAssist Pro layout, it will then use whatever values you have specified when creating the menu for the widths and other css. Here is a link to the SiteAssist Pro support page that has this How To on it:
If you have any trouble with any part of this let us know so we can help you get it worked out.
To neilo, sorry about the troubles you are having, I assume that you are referring to CSS Menu Writer in regards to adjustments you are making to the text and widths, or are you talking about CSS Sculptor? There is no interface within SiteAssist Pro for these settings so I'm a little confused about this part. Please post back with this info and the steps you are taking when you make the edits and they do not work for you, I will make sure that I do some thorough testing of this to see if I can get the same to happen. If not I may need to open a ticket for you so we can check this out further.