
There are grey spaces on both side of the Power Apps screen when embedded in an i Frame in a html page. Any suggestion to removing the spaces?
The only way to remove that grey space is to adjust the actual canvas size of the app using responsive design techniques. That requires turning off certain autosizing options in the settings and programattically setting the height and width. It does require a fair amount of effort because removing those spaces will change the layout of every control on the screen. So you'll need to adjust all of them. You can read about how to do responsive design in Power Apps here:
https://docs.microsoft.com/en-us/powerapps/maker/canvas-apps/create-responsive-layout