Yeah I found the same problem The top part is covered. But I cannot re upload again when i found this problem because the system is closed. Firstly before the system is closed, I try to change the background color makes looks not clear. But it cannot solve the problem. Thirty minutes ago I try to change the default webGL resolution from 640x360(default) to 960x540. But also one top part cover my game. My teammate said some game canvas size would change a little bit when the game is compressed to WebGL.(Maybe true I am not sure). She said 1024x768 would be best choice next time.
Thanks for your likes and recommendations~have a great weekend~