We should use 'transparent' black at least.
Created attachment 641774 [details] [diff] [review]
I couldn't make the black and blacker (without making it non-translucent) so I've swapped the highlight colors.
Not to say that this one isn't also without problems because we have off-white text too.
Does this help?
Comment on attachment 641774 [details] [diff] [review]
This is an improvement in contrast, but I feel it's not enough contrast. I would suggest background-color: #000; color: #fff. I tested this and it looks better.
Not sure if there's any benefit/requirement to have the highlighted element translucent.
Leaving the final choice to you. Giving r+. Thank you!