Window scrolls whenever character in game jumps

I have a game online (http://roomrecess.com/Haxe/TimeHunter/play.html) that when played on a desktop/laptop has a small glitch. Whenever the character jumps (up arrow) the entire pages scrolls. I have several games on my site with the same type of function and am not sure why this specific game does this. Also not sure if I need to post HTML code or Haxe (game) code. Any suggestions?

Doesn’t happen for me on macOS Safari. It’s probably browser specific?

Sounds like there needs to be an event.preventDefault (), I’m not sure if we’ve wired things so doing that on an OpenFL keyboard event will trigger it, but it may be a worth a try.