DatePicker styling

I use the inline DatePicker. When the page is loaded the current date is pre-selected and visualized with a blue background. But no date is selected yet.
When the user is selecting a date the same blue background is used to indicate the selected date.
This is confusing. I would like to style the current date differently from the selected date.

I looked at the used css classes but I can't figure out how to do this.