a good site overall but a little boring from the design
It depends on each player perspective as Rollbit interface is liked by many with dark mode theme and easy to navigate interface but the main thing should be casino should be legit and games should be fun and exciting for me personally and it's good you liked the site and some new development can improve interface more.
That is understandable because at the end of the day if the casino is legit but you are not having fun with it that could mean that you do not want to continue gambling anyway.
There is no single legit casino, there are other casinos which are legit as well and if you like the design of it then you could gamble there. I like the dark theme here, personally this is better than most places, there is one other place, which does insane marketing and has amazing design, and I gamble there because of those two reasons and they are legit too but they have horrible odds and house edge and yet I still gamble there, sometimes marketing and design matters that much.