Unable to style day cell

[t-zander]

Describe the bug
I am unable to style date cell, in any way. I've used modifiersStyles.
I need it because for some reason I have white color of days and white background on hover.
As far I got it, I can use any of these

Here is the code:

const styles = {
    today: {
      color: theme.palette.primary.dark // it comes from MUI react (I haven't found any clear way to combine their makeStyles utility with react-day-picker
    },
    selected: {
      backgroundColor: theme.palette.primary.main
    },
    day: {
      color: "red" // doesn't work
    }
  };

<DayPicker
        selectedDays={selectedDays}
        onDayMouseEnter={handleDayMouseEnter}
        onDayClick={handleDayClick}
        numberOfMonths={2}
        months={MONTHS}
        weekdaysLong={WEEKDAYS_LONG}
        weekdaysShort={WEEKDAYS_SHORT}
        firstDayOfWeek={1}
        modifiersStyles={styles}
      />

To Reproduce
https://codesandbox.io/s/react-day-picker-base-8b440

Expected behavior
Screenshots
https://prnt.sc/q4o2bq
Additional context
I am on Next.js
I am using material-ui react
No css modules, only MUI tool called makeStyles()

[KyorCode]

I don't think 'day' is a default modifier, therefor not being able to be styled this way.

However you can use renderDay to use your own component, which you can style anyway you want.
https://react-day-picker.js.org/api/DayPicker#renderDay