Aww yeah, Material-UI v4 is here!
App Bar

App Bar

The App Bar displays information and actions relating to the current screen.

The top App Bar provides content and actions related to the current screen. It’s used for branding, screen titles, navigation, and actions.

It can transform into a contextual action bar or used as a navbar.

App Bar with buttons

News

Simple App Bar

Photos

App Bar with a primary search field

A primary searchbar.

Material-UI

App Bar with menu

Photos

App Bar with search field

A side searchbar.

Material-UI

Dense (desktop only)

Photos

Bottom App Bar