If you have opened a Google document, spreadsheet, or presentation in a web browser on your mobile device in the past week, you may have noticed that Google is rolling out a new look.
The updated interface is simpler, and the changes are consistent across all three services. An action bar stretches across the top that lets you go back or start editing. The title of the document sits in the center. In most cases the bar is gray, but it turns dark when viewing slides.
Google is taking this time to phase out the ability to edit Docs files on the web. For now it will just prompt you to download the app, but in the future editing will require it. This will put it in line with Sheets and Slides, which already need their respective apps.
The look has been rolling out over the past few days, but it may still be a work in progress. If you don't have it yet, just give it a bit more time.