Customizing themes: Remove element from existing theme vs. import font-related styling to new theme?

Hello all,
Apologies for the newbie CSS question... I've done a fair amount of customization at the page/item-level (combination of JavaScript and HTML + CSS), but I have limited knowledge of CSS stylesheets and how to customize the styling for an entire survey.
Here's the issue: I created a (complex & highly customized) survey using one of my university's static custom themes.
I like almost everything about this theme except the fact that the bottom blue bar/line makes it very apparent that we are using automatic page advances rather than truly interactive elements where things pop up after dynamically, e.g. after a "loading symbol," etc. [This is an experiment; the cover story is that participants are actually assigned to real teams for a volunteering task where they are able to send messages to their teammates. Reality is that the "teammates" are pre-programmed by the researchers.]
If I inspect the page when previewing the survey with this static custom theme, I can view the following stylesheet:
Custom stylesheet copied from Inspect element.txtI've figured out how to (mostly) suppress the "Powered by Qualtrics" element (using custom footer code under Look & Feel), but cannot figure out how to suppress the bottom blue line.
Failing being able to remove/suppress the bottom blue line/bar, I tried to use a different static theme. The only one that was anywhere near similar enough is "Minimal 2014" under the Old Look & Feel Editor (which seems to be increasingly non-functional). Unfortunately, the default fonts and stylings aren't quite right, which making some of my customizations display oddly/poorly. I'd rather not have to go through and manually adjust all of the styling.
I feel like there ought to be a straightforward way to suppress the display of the bottom blue bar in the custom university theme OR to import all of the font-related styling to a new theme. Can anyone advise?
You can view an earlier test copy of the survey here, in case it provides additional info you might need: https://ubc.ca1.qualtrics.com/jfe/form/SV_9T4PKlyd2wRhRPg
Thank you so much!