Comment 5 for bug 1694624

I don't think that's too bad, you have the contrast difference already so even in monochrome you would be able to see in the indentations. I could suggest maying the brighter bit at the end of the line on the knobs just a little bit bigger or brighter in colour but that's about it....

It's also acceptable to have on High Contrast skin, which would be perfectly viewable in monochrome/b&w, which I think it's worth checking for the most common red/green colour-blindness on the rest I'm not sure you need to make sure all of them are find right down to the contrast/brightness only level.