It better be red. Different colors and different occasions mean different things. It's just that you don't pay attention to these etiquette yourself, other guests, or your in-laws, don't like it, and maybe your mother won't either. I suggest you usually wear red. I saw a pink cheongsam when I got married and wanted to propose a toast. But the aunt who sells cheongsam told me that pink is for second marriage. Fortunately, she reminded me in time, otherwise it would be a joke.