How to edit blocks

I would like to combine the capability of including a popup image of a downloadable file/pdf and the [Download File] button within the same block. As far as I can tell, you presently require two blocks to achieve this, an image block and a download file block. I searched for the css that appears to be used in the download block (eb-file-details) in hoping to find and edit the file that is used for the download block. However, I was unable to find the css "eb-file-details" term in administrator/components/com_easyblog, components/com_easyblog, nor in any of the modules or plugins.
Please advise.
Thanks
Jim