Darken Gmail with Gmail Redesigned

Firefox with Stylish: The Gmail Redesigned user style—which requires the Stylish extension to use—skins Gmail with an attractive, well laid-out, and completely overhauled look. Everything in the Gmail Redesigned interface is darker and a touch sleeker than the default Gmail interface, which hasn’t changed all that much since Gmail launched four years ago today. Right now the developer is issuing updates to this style almost every day. Once Gmail Redesigned is complete, we hope to add it to the rest of the Gmail skins in an upcoming release of Better Gmail.