How to change width and other classes in react-datePicker using react-emotion

Question

I'm using react-datePicker and I want to style container and few other classes using emotion-react. Can You please suggest how should I properly do it ? My datePicker looks like this:

<DatePicker
          className={datePicker}
          selected={startDate}
          onChange={onChange}
          startDate={startDate}
          endDate={endDate}
          selectsRange
          inline
          showYearDropdown
          showMonthDropdown
          renderCustomHeader={({
            date,
            prevMonthButtonDisabled,
            nextMonthButtonDisabled,
            changeYear,
            changeMonth,
            increaseMonth,
            decreaseMonth,
          }) => (
            <CustomHeader
              date={date}
              prevMonthButtonDisabled={prevMonthButtonDisabled}
              nextMonthButtonDisabled={nextMonthButtonDisabled}
              changeMonth={changeMonth}
              changeYear={changeYear}
              increaseMonth={increaseMonth}
              decreaseMonth={decreaseMonth}
            />
          )}
        />

and this is how I want to style it adding className:

const datePicker = css`
    width: 80%;
    border:none;
  `;

with this code I'm getting such error:

can You please suggest how should I style container and also other classes of datePicker, like for example .react-datepicker__header

thanks