In "The Masque of Red Death, which details about the 7th room make it grotesque in appearance? What mood is created by this setting?

Several details of the seventh, westernmost, room make it seem grotesque.  First, the walls and ceiling are hung with black velvet, a color and a cloth that seem to suck up and absorb all light; even the floor is draped in the same fabric and hue.  Second, the windows are stained red, "a deep blood color," casting a scarlet tint on anyone who actually dares to go into this room (and not very many do because it is so frightening to look on the faces of others here).  Further, the light of the fire from the tripods just outside the room, streaming through the "blood-tinted panes was ghastly in the extreme."  It rendered the courtiers' faces "wild," and almost inhuman.  

These details, which seem to distort the revelers into something terrible, inspire quite an ominous mood.  The fact that black so often symbolizes the unknown, and even death, and that the windows' color is repeatedly described as being like "blood," is terribly foreboding.  Further, the fact that all the masqueraders stop and grow pale at the sound of the clock that chimes loudly in this room is yet more productive of a strange sense of anticipation, the feeling that something awful is going to happen.