Uhmm, an honest opinion in terms of design, honeslty I do not like the overall design of the casino itself.
It is good in desktop mode, but when it is currently not a mobile-user-friendly.
The elements of the main menu (bottom-middle) are too big, the animation of the opening & closing the sidebar menu in mobile screen is cringe... lol.
Certainly, you might need to work more on the UIUX design aspect of the website.
Almost all casinos that are launching themselves come up with the same template for design. I did not find their UI/UX bad, it is eye-soothing and grabs the attention of anyone visiting their casino. I did check their website on mobile devices and it is fully compatible and easy to access on mobile devices without any issue. The desktop version is good too, but I do not understand why you have written that it is currently not mobile-friendly. They have a slider on the home page which is not that big. All the games are displayed below the slider and you can access the menu by clicking on the hamburger menu at the top left hand. Everything looks perfect and it is not that bad as you have written.