Higlight a multi-step form


I have an Landing page with a multi-step form and I added a black div with transparency so when the user click anywher of the body the black dic appear covering everything except the multistep form. But somehow using z-index for this is not working once that I’m changing the z-index from the built in Unbonce components using css but nothing works. It appears that the unbonce components have original 15+ z-indexes, but if I give my div any z-index higher than 1 it seats on top of everything.