I am building a single storey lean to extension on to the back of my kitchen. It will have a corner window, velux windows and patio doors going out to the garden. I would like to go for very dark cream window frames on the outside but there are two white windows on the first floor which will be visible above the extension. I am worried about the different colours & how it will look and wonder if anybody has done or seen anything similar? Any opinions would be much appreciated.