Horizontal grid lines - Can they be made more prominent?

[gm22]

While using volume automation, I just noticed very fine horizontal lines in 6dB increments, but they're incredibly faint, in fact, almost invisible. They can be made more visible by using time selection, but the grey-ish background of time selection then obscures other elements one has to work with.

Is there any way to make them more visible? I'm using Imperial White Tie theme.

[hexSPA]

I never even noticed they were there. After looking in the theme tweaker, I don't see an option for changing their appearance.