Aww yeah, Material-UI v4 is here!
Positions

Positions

Use these shorthand utilities for quickly configuring the position of an element.

z-index

<Box zIndex="tooltip">
<Box zIndex="modal">
z-index tooltip
z-index modal

API

import { positions } from '@material-ui/system';
Import name Prop CSS property Theme key
position position position none
zIndex zIndex z-index zIndex
top top top none
right right right none
bottom bottom bottom none
left left left none