Now for something completely different, auto image/video size adjustment for vertical vs horizontal screens.
I like playing html games on my vertical screen because it uses the screen space more efficiently, but oftentimes image/video content get unnecessarily scaled down.
Example picture in spoiler:
Horizontal:
Vertical:
(You would need to open the full picture and zoom to 1:1 scale to see that the vertical one has a scaled down image)
This is an issue with a lot of html games and I'm not sure if there's an easy straightforward fix but devs don't think about it, or if it's a troublesome thing to get right.