Hi Gary,
Good question. A method I use, although perhaps not ideal, is to open my Preview page using Safari. Right-click on the page, select “Show Page Source”, select “Fonts” or “Style Sheets”, and navigate until you find the material you need. With some minor sleuthing, you can determine the specific page and location of the offending material and then return back to Sparkle to remove/change as needed.
Hope this helps.
