Change Caption Position [Widget Calendar]

Hi,
I need to style my calendar, so it becomes like this link: https://goo.gl/4NuDVU.

This positioning to the left of the <caption> where is the month and year, can only be done with css? How would I align this element to the left?

I tried changing the file ‘class-and-calendar-widget.php’ but did not work. Very confusing for beginners!

Thank you for your help,
Lucas
https://www.ads-software.com/plugins/event-organiser/