Background color on days with events

If you go here: http://svsite3.com/location/
Look at the calendar widget.
You will see on days with events, the color is yellow. I don’t like that look. How can I make it transparent just showing the date with it’s normal link color.

I have looked at elements but can’t figure out what the custom css would be or where to edit in the calendar style sheet.

Thank you

https://wordpress.org/plugins/spiffy-calendar/