how do get rid of or set to black, comment backgrounds?

Just recently some kind of update must have happened because now whenever I look at comments on a post they all have grey backgrounds even though my look and feel theme is set to AMOLED and previously they were black unless specifically selected.

I went through the settings and found there was an option called "background" it doesn't specify that it's comments but I assume it is as the colour matches but the colour choices are a limited set that somehow don't include black with the darkest I can go to being the same grey it just got set to.

I chose the dark theme for browsing at night so if a large portion of the screen is grey then it will be a lot brighter than it used to be and the white text will be less distinct.