Brown Mule

Are there any rules for sock color when you wear mules?

I normally wear tennis shoes, but I just bought some brown mules. I only have white socks, which looked really weird to me. What would be better?

I have a pair of black mules and wear dark grey or black socks
so tan maybe go with a brown or dark tan color
but my step daughters have a tan pair each and wear white socks but there are 11 and 12

KC35 KISSING CRANE LARGE BROWN MULE