Hi Dustin,
Thanks so much for your report!
This is exactly the right way. The accordion content-wrapper is either hidden (display: none) or shown (display: block) using a style tag. Since the style tag has a higher specificity than your class, it does not work using a class.
However, it would also not work with styling on the ID, as the accordion would then no longer work as expected The same applies to the tabs element (1|2|3).
Best regards,
timmse