How to change the colors in the Web Client?

The colors used on the Web Client are defined in various style sheets. You can use these to change the colors as you like. The style sheets (*.css) can be found under
C:\ Program Files \DocuWare\Web Client Server\Web Common\DocuWare\Themes\DocuWare\
in the relevant subfolders. For example, the style sheet for the default result view is located in the DWGrid subfolder. You can see which colors are used for what from the comments in the style sheets.

If you had customized style sheets and you want to continue using these after installing the update or service pack, you will have to edit the new style sheets accordingly. You cannot simply copy the old style sheets into the new path.
You will find the old style sheets under the folder Web Common.BeforeUpdate_<Date>_<Time>. You can copy your changes from the old to the new files.