Well, I don;t know web report studio particuarly well. What I would say is there is a difference in the use of SAS templates and CSS files. A template applies to output as it is generated from SAS, i.e. the file is created there is no other files, all styles and layouts are in that file. Thus to apply another style to the document later on is quite difficult, however the benefit is you only get one file, so easy to distribute.
A CSS file on the other hand is a style which is applied at render time. So you have two files, the data, and the css which shows how to render the data. This is useful as you can change the style easily, and re-render the data, however you have mutiple files, and only certain applications can load and render.
Generally speaking I would say that CSS would be bettter if the data is to be rendered on many machines which may have different resolutions/setups as then it is dynamic. Template and one file would be better if you need to manually send files around, or if a specific file format is required.
