Here is a photo from further away for perspective.

paint them the same color as the wall.

I chose the darker color on purpose over buying white.

Oh I see what you’re saying lol. Paint the screws! Haha sorry I haven’t had enough caffeine yet.

Paint the brackets and the screws to match the wall color.

Painting the wall color is probably the easiest (if you have a long arm). The brackets aren't really that bad. The bookcases look great, by the way.

Ya know, I think IKEA used to have plastic dohickeys that covered those, and they could be painted. I remember throwing some away!