chatwindows on end of the page

[SebulonIsme]

On at least facebook and okcupid, chatwindows are at the (as in: scroll down to the) bottom of the loaded page instead of floating at the bottom of the window screen. That is a problem on facebook since there touching the bottom of the page initiates more content to be loaded - and the chatwindow is farther down again.

[Max-Github]

I do not use these website so it is hard for me to debug this issue. Are you able to see what is actually causing this?