A footer component with full material-ui themed structure is required.
Generic material components have a key in the getMuiTheme object (dark.js). Quote:
This object contains the following keys:
spacing: can be used to change the spacing of components.
fontFamily can be used to change the default font family.
palette can be used to change the color of components.
zIndex can be used to change the level of each component.
isRtl can be used to enable the right to left mode.
There is also one key for each component so you can use to customize them individually: