Most of the people these days dev sites just so that they can make it work on chrome and that's it. They dont bother to check whether it works on Firefox
Problem is in html5 game beta and not in the website, their development should have tested the game on several browsers to make sure it works fine before publish it, but I think maybe because many people here ask them to launch web version as soon as possible and that's why they rushed to release it before fixing those flaws. Anyway, I don't that a big problem, it will be fixed in upcoming version, I'm more concerned about minimum deposit which is $100!!