If any of those were actually distinctively associated with a particular brand, I could see an argument being made for it. I think the key to how reasonable it

If any of those were actually distinctively associated with a particular brand, I could see an argument being made for it. I think the key to how reasonable it is to trademark it depends on how widely it's enforced, both in terms of industry and in terms of how much of the color is involved. In this instance, a magenta banner is associated with a company that offers insurance products - and another company is offering insurance products and using a magenta banner in their branding. I think it's actually a fair question whether that crosses a line.