If you want to embed a palm-sized mirror in the courtyard door, it is recommended to put it on the top of the door frame, that is, the horizontal position of the couplet (the highest position is better)
If you are at the left and right doors of the gate, it is not recommended to install mirrors. The door is the entrance of gas. Mirrors are mainly used in geomantic omen, but it is also easy to keep the good ones out.