In the recent days, you would have noticed the changes in the Google search and Google Maps homepages. Two new similar themes for Gmail are now released by the Gmail team to give a sneak preview of the changes.
This is part of a Google-wide effort to bring you an experience that is more focused, elastic, and effortless across all of Google products. The Gmail team is working on these upgrades gradually over the next few months to allow plenty of time to understand and incorporate user feedback into the evolving design. Gmail team states that, the new interface will eventually expand dynamically to accommodate different screen sizes and user preferences. Like Gmail, Google Calendar is also getting a new look within the next few days.
As the first step, the team has annoucned two new themes for you to try out as a sort of sneak preview. In Gmail Settings, go to Themes tab and find the two new themes at the end : “Preview” and “Preview (Dense)” themes.