The rack suggestions work. If for whatever reason a rack doesn’t work, I have had great success placing a piece of equipment that is not ventilated (like a tuner, streamer, power conditioner, tape deck, etc.) above the ventilated equipment with some risers to allow sufficient airflow for the ventilated equipment. If you don’t have such equipment or it is too bulky for this approach, just get a properly sized piece of wooden shelving and use that as a cover.
This approach also works well as a way to handle family members who persist in placing things on top of ventilated gear without being a constant nag.