Getting keyboard marks on screen which cannot be wiped off. Is little bit marks normal? They are visible from the sides or when light is hitting the screen directly. Firstly, I was not worried as I thought they can be removed, but they remain and does not go. I don't put the laptop in the bag, I don't take it outside, so there is no pressure at all. It remains pressure-free and kept with full care. Still why there are keyboard marks?