Hey there. I like the design of the site and the game play. The site is quite responsive after it loads. Some remarks:
1. The site takes some time initially to load for the first time (~30 seconds). I guess you could improve the performance a bit. If that is not the case and it's my ends fault disregard this,
2. On the history add a link where it will lead to the provably fair scheme for each round where you can verify the round.
3. You should be able to set your own amount for bet. You can only set the minimum (20bits which is fine) and multiples of that by 10.
Good luck with your site.