JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/redmond/jquery-ui.css">
<input class="date_field"><br>
<span style="z-index:9999999999; position:absolute;">ugly overlay</span>

JavaScript

$('.date_field').datepicker({
    //comment the beforeShow handler if you want to see the ugly overlay
    beforeShow: function() {
        setTimeout(function(){
            $('.ui-datepicker').css('z-index', 99999999999999);
        }, 0);
    }
});