Anyone other red-green colour blind people having difficulty telling whether items are correct or not from the colours? I am struggling on iphone. Skritter people - any chance the contrast on these could be increased?

I'm not sure how much it would help, but you could try inverting the colors on your screen which might help a bit: iOS Settings > General > Accessibility > Invert Colors. You can also set that up to trigger by triple tapping the home button, which is also under the accessibility options.

Jeremy thanks a lot, that's very clear inverted albeit the colours are all a bit trippy. Also noticed that the dark colour scheme is less clear than the other one for me, so changed to that. Edited to add it's quite a bit faster to respond on the light colour scheme, so overall improvement - great. Cheers.