May i change the calendar background color ?

I want to set some days to holiday, SO i need to change some days background's color to red.

I had found the solve
var dayDiv = angular.element(document.querySelectorAll('[tabindex="' + 17 + '"]'));
dayDiv.css("background-color", "#ff0000");

when i click next month, document.querySelectorAll('tabindex="'+17+'"]')); will not find current div change the background color.

what should i do? 