As soon as you position something like that absolutely, it is removed from the document “flow”, which basically means that all other elements will kind of disregard/ignore your block and not place themselves around it.
So, it is now ABOVE the menu. If you would move it to BELOW the menu, by keeping it absolute but just a different top coordinate, anything else on the page will not change or move. If that’s what you want — great! If not, I would advise against using position absolute.