By default, DITA2Go includes line leading (spacing) information in the CSS file. In some cases, this is not desirable; for example, it messes up printing in Netscape 4.x. You can turn off line leading:
[HTMLOptions] ; UseCSSLeading = Yes (default) or No (omit linespacing in CSS files) UseCSSLeading=No
You might have to make some changes to your paragraph formats to get CSS to yield good results, especially if you are trying to get those CSS results out of Netscape. For example, Netscape does a poor job with margin bottom, but renders margin top, equivalent to Space Above, reasonably well.