The flat top in the store is black. Is it related to Feng Shui?

This question is very biased. From the perspective of geomantic omen, if black is used as a large-scale color tone such as floor or ceiling, there are two kinds of black roofs that can be seen at ordinary times. One is a temple (which is rarely used now, but usually the roof of the temple is decorated even though it is black), and the other is an extremely sunny person. Such people are rare and basically don't need to be considered.

so I suggest you change the color. (In addition, a wide range of red is extremely yang, so don't use it, for the same reason.)