I'm seeing what looks like a false negative for the Linter "night-mode-unaware-background-color" error in en:Template:infobox royalty. In this version of the sandbox, we have this formatting for the parameter "succession":

| headerstyle = background-color: #e4dcf6;line-height:normal;padding:0.2em 0.2em

In that code, I see a background-color defined without a corresponding color, which I think should cause a night-mode-background Linter error when the infobox is rendered. In this forced dark mode view of the testcases page, the value of "succession", "Queen consort of England", shows as black text on a black background, which is an error. The testcases page reports no Linter errors, but it should.