You can try to uncompress the files and edit the HTML to not use the .gz files.
Also, in my own expierence with HTML5, there is a issue causing a Syntax error, returning ILLEGAL token.
To fix this I had to experiment with the .htaccess file as the documanted suggestions aren’t sufficient.
In the end I ended up using a .htaccess of some random community board that had a lot in it, fixing the SyntaxError. But I need more time to narrow down what did the trick in the .htaccess.
Look at this page: https://answers.unrealengine.com/questions/296709/html5chrome-syntaxerrorunexpected-token-illegal.html
It helped me a lot to get in the right direction 