I am trying to override a class that is used in the following file:
C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\LAYOUTS\XLViewer.aspx
Unfortunately this file does not inherit from the masterpage and I cannot use my existing custom css file to add the new style.
I would like to avoid modifying the out of the box sharepoint files if possible which eliminates adding the style directly to the aspx file or changing the style in the original css file.
Are there any other ways to do something like this?