Yes, that was exactly the problem: the container in my WebWork version is called problem_body. I now got it to work just fine. I experimented with various settings and I think the best result is by keeping the opacity of the watermark to only 0.1, and then make all the text of the problem in bold, as well as all the LaTeX content in math mode in bold (this can be done by using \boldsymbol{} ). Then I think the watermark does not interfere much at all, but it is still visible, also when I take a photo. I repeated the same line (with smaller font) throughout the page. I feel that this is going to be quite a deterrent for cheating. Thank you for your help! I couldn't have done it by myself.
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Prevent cheating in Gateway quizzes
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