Shadows imply elevation, and bigger shadows imply more elevation. If we use shadows strategically, we can create the illusion of depth, as if different elements on the page are floating above the background at different levels.
Here's the first trick for cohesive shadows: every shadow on the page should share the same ratio. [...] To ensure consistency, each shadow should use the same ratio between these horizontal and vertical offsets.
By matching the hue and lowering the saturation/lightness, we can create an authentic shadow [same color style] that doesn't have that “washed out” grey quality.
I will think about it the next time I will have an interface to build.