Aww yeah, Material-UI v4 is here!
Sizing

Sizing

Easily make an element as wide or as tall (relative to its parent) with our width and height utilities.

Supported values

The sizing style functions support different property input type:

<Box width={1/4}> // Numbers in [0,1] are multiplied by 100 and converted to % values.
<Box width={300}> // Numbers are converted to pixel values.
<Box width="75%"> // String values are used as raw CSS.
<Box width={1}>   // 100%
Width 1/4
Width 300
Width 75%
Width 1

Width

<Box width="25%"><Box width="50%"><Box width="75%"><Box width="100%"><Box width="auto">
Width 25%
Width 50%
Width 75%
Width 100%
Width auto

Height

<Box height="25%"><Box height="50%"><Box height="75%"><Box height="100%">
Height 25%
Height 50%
Height 75%
Height 100%

API

import { sizing } from '@material-ui/system';
Import name Prop CSS property Theme key
width width width none
maxWidth maxWidth max-width none
minWidth minWidth min-width none
height height height none
maxHeight maxHeight max-height none
minHeight minHeight min-height none