How does rootMargin work in InViewport?

[victormihalache]

I can't really find anything in the docs about it. It only works with a string that ends in px, but not rem... So where is it used in the code/how, as in: what values does it accept? Can it accept a multiple of the height of the target element?

I am using this to show a floating button when the CTA in the hero section is not visible, but I found out that the requirement states that the floating CTA should be visible when the CTA in the hero is 3 times its height from the top (aka, if you can fit 3 times the button above it, don't show it, but if you go below these "phantom" buttons, it should show the floating CTA. I can kinda replicate it by putting a pixel amount, and I could compute it myself, but it seems... wrong.