Brown Gmail.com users will start to see a new UI that Google is pushing out to all Gmail accounts. You can learn more about changes in Google's support article here.

To immediately opt-in to this new UI change or roll back to the previous one*, follow these directions:

Opt in to the new view

Important: To use the new view, you must turn on Chat in Gmail and set Chat to the left-hand panel. Learn how to turn on Chat in Gmail.

1. At the top right, click Settings.
2. Under “Quick settings,” click Try out the new Gmail view.
3. In the new window, click Reload.

Opt out of the new view*

1. At the top right, click Settings.
2. Under “Quick settings,” click Go back to the original Gmail view**.
3. In the new window, click Reload.

*As with all other Google UI changes, it's likely that rolling this back is only temporary and you will be forced to move to the new UI eventually.

**When reverting back to the original view, Google will ask you why you're making this change. You can leave this blank.