There's been a patch for months adding the CSS dark mode support to the git.kernel.org cgit web interface while now it's finally been rolled out.
Yesterday it was noted on social.kernel.org that the dark mode support has been rolled out for git.kernel.org to enhance the viewing experience of browsing the official Linux kernel Git as well as the many development branches housed there.
As an extra plug, if you are looking for native dark mode support on Phoronix, that is available via Phoronix Premium .