i stumbled upon "dark theme material pro":
It looks a lot like the dark theme that comes built-in with the Brave browser.
I see we have a "brave" fan here!
Well, did download Brave to compare and its default dark, or dark theme from Chrome store or even Windows dark settings still not as nice.
The "Dark Material Pro" installed for Slimjet has greyish tone for inactive tabs, thus making the active one more noticeable.
Themes aren't everything, but when i find a nice one, i stick to it for a long time.
Slimjet's bookmark autohide and scroll through tabs with mouse just enhances this feature.