I am using a Surface Pro 1 (original Surface) which was updated to Win10 a few weeks ago. I have noticed a few more glitches with Edge on this machine that seem to be related to the last screen orientation on power off. For example if the screen is in portrait (vertical), the browser is in the foreground and the machine is turned off, if you start it the next time in landscape mode (horizontal) the browser (Edge) does not render properly. You have to shut Edge down and restart.
I have since noticed this same issue other applications such as Kindle reader so it appears to be an issue with the Surface/Win10 in general and not Edge/this website in particular. It just happened to be when viewing this website that I first noticed it.
Now to figure out how to submit this weird bug to Microsoft