The background closest to the old Gmail is the solid "soft gray" background option. To truly match the Old Gmail background, you would want "white," but that's not an option.

Once you do that, you’ll see a small, rectangular menu pop up to the side, with text that reads, “You’re using the new Gmail view.” Under that, click Go back to the original view.

Google’s new Gmail logo looks a lot more Google-like now. The new Gmail logo includes Google’s four primary brand colors, and ditches the iconic envelope in favor of simplicity.