By “background: none” on the Entities card level you made the whole card transparent - now you see a “view background” color (black, I guess).
The “divider-row” color uses some “card’s color” for a text label: it is not “line on the left, some text, line on the right” - it is “one long line + an overlaying text in a rectangle”.
If you need this “rectangle” to be of some particular color - then you need to style THIS “rectangle” as well.
Here is a link to a PROPER place where you should have started asking card-mod related questions. As for that “rectangle” - check the 1st post in the mentioned thread → link at the bottom → styles for text-divider-row.
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