uppercase first letter of month fullcalendar

Can anyone help me uppercase the first letter of the month in fullcalendar? When I write the fullcalendar, I found that the in English, for example August, the display of month in title is correctly "August" or "Aug.". But in Spanish the first letter of the month is not capitalized. For example, "Agosto" and "Ago." is "agosto" and "ago.".

Is there any way to correct this using css or the only way is to change the locale_all.js file?

By using CSS, you can easily capitalize the first alphabet of the title (month).

please use this .fc-toolbar { text-transform: capitalize; }

or you can also check the link First capital spanish letter