Changing next button margin-top in a multiple choice question

Hi Everyone,
I've used the code below in the question-text HTML on a text/graphic question, and it worked absolutely fine. It moved the next button far down the page.



However, it doesn't work when put into the question-text HTML for a multiple choice question. Does anyone know a fix?
I'm trying to hide the next button and I need to prevent people seeing it flickering when the page is loaded. Moving it to the bottom of the question page achieves this. The question is timed so the next button isn't needed.

Thanks so, so much!! Really appreciate any help.