When overriding my color selection, It does not change the color of the transition animation upon being selected. What is the issue?

      <DateCalendar 
      defaultValue={dayjs("2022-04-17")} 
      sx={{
    "&& .Mui-selected, & .Mui-selected:hover": {
      color: "white",
      backgroundColor: 'black'
    },
    boxShadow: 3,
    borderRadius: 5,
      }}
      />

Attempted modifying sx component but doesn’t seem to update.