I created a FreezingOverlay element, which can be activated by drinking the Potion of Freezing, but the Overlay does not scale properly to the screen.
I have tried both a 256 x 256 and a 1920 x 1080, as suggested by NorthWestTreesGaming in his video. Even resizing my Minecraft screen to a smaller size did not scale it properly.
When changing the image size, I made sure to reenter and exit the element. but it still didn't adjust correctly.
When changing the image to 1920 x 1080, I checked the code and changed the 256 x 256 to 1920 x 1080, which seems to have fixed it. So it seems that the code isn't changing to the proper image size.