Hello,
I see that you've made a very large embed window right now. This is a bad experience for people who have tinier screens. We do not support having the game embed change dimensions on the game's page, you'll have to use the mode that opens your game in fullscreen.
As a side note, there's nothing special we do about embedding your game other than putting it in an iframe. If you're having an issue with your game changing shape then it's likely related to your engine configuration, or you may need to call a method in your game engine to maximize it.