Very nicely done, enjoyed playing it! My only wish would be to hit after split, though the way you handled it is perfectly valid.
The Wizard of Odds has a very thorough walk-through of the variations of rules - and what they mean to the odds:
https://wizardofodds.com/games/blackjack/basics/#toc-RuleVar...
Brings back memories from playing many, many hours of playing optimal strategy blackjack to release generous bonuses from online casinos. :)
Well done on launching btw. I second the UI suggestions about making UI a bit easier.