Gmail is the next Google app to get a new look. From now on Gmail gets the same style as the other apps that have been updated with the new Material Design.
The Material Design
A lot of the Google-apps get a new minimalistic theme also known as the Material Design. This new theme looks like the new brand style. in earlier updates apps like Google Maps, Contacts, Calculator and even the Google Assistant got a new style.
Gmails new look: what's new?