Thanks for sharing.
I understand you don't want to end up customizing this plugin for all and sundry, so it would help you ~ and me/us ~ if you'd post a list of the CSS elements we need to address, for those of us not fortunate enough to have authors who created predefined CSS in the child theme we bought.
It would also be very helpful, if you were feeling very generous, if you could post together with it, a sample (default?) css configuration and make them both available as a sticky on this forum.
Might save you a lot of support questions.
Would save us a lot of time, head-scratching and coffee.