LPS-40938 Side panels should addapt to fit the phone screen size

Hey @marclundgren

You'll have to test this on an actual mobile device to understand why I did what I did. I removed a lot of the fix positioning for phones because when the inputs in the add panel are focused and the keyboard pops up on the phone the fixed elements took up too much of the screen space, covering the focused input.

The reason I made the add panel static, is that it more or less mimics the current behavior on a desktop view. It's just instead of the panel taking up horizontal space and pushing the main content to the right, it takes up vertical space and pushes the main content down.