What to wear underneath graduation gown?

well im graduating middle school in a few days and my gown is red or black lol prob red and for religious reasons i cant show my legs ( i do n e way) t my parents are gonna be there so yea have to cover da legs so no dress or skirt so i wuz thinkin mabe i shud wear lke a really long tee or dress with leggings/tights (idk which it is mostly leggings dat dont go over my ankles n r not see trough) n e way yea leggings/tights underneath with mabe flats cuz i heard from a teacher a chic wore heels dat day n theres a ramp there n she slid down so flats it is wud dat work or wut?