JSFiddle - React, Tailwind, and code Playground
HTML
<div id="datepicker"></div>
CSS
.ui-datepicker-prev span {
background-image: url(http://legacy.australianetwork.com/img/icon_arrow_left_black.png) !important;
background-position: 0px 0px !important;
}
.ui-datepicker-next span {
background-image: url(http://legacy.australianetwork.com/img/icon_arrow_right_black.png) !important;
background-position: 0px 0px !important;
}
JavaScript
$("#datepicker").datepicker();