My document is a workbook, which is designed with a particular style
designated for the answers to appear in red when printing the teacher
version of the workbook; when printing the student version, I change
that style's font from red to white. This makes the answers disappear
and would work perfectly except for the fact that there is a gray
watermark in the background; any answers that cross the watermark show
up. I was wishing for the ability to make the text transparent instead
of white...is that possible?