The new hamburger menu hovers to the side of the page on fixed-width layouts with non-white backgrounds:
It slides in fine and I can fix the white rectangle using the slideright style, but it also clips over profile cards.
Closing this, the Jury is is still VERY much out about if it will slide out on desktop.
It should slide out based on the width of the layout relative to the viewport. If the viewport is large “enough”, it can drop down instead.