JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://arshaw.com/js/fullcalendar-1.5.3/fullcalendar/fullcalendar.css">
<script src="http://www.arshaw.com/js/fullcalendar-1.5.3/fullcalendar/fullcalendar.min.js"></script>
<div style="border:solid 2px red;">
        <div id='calendar'></div>
</div>

CSS

.fc-sub-event {
    border:solid 1px black;
}

JavaScript

$(document).ready(function() {

    var date = new Date();
    var d = date.getDate();
    var m = date.getMonth();
    var y = date.getFullYear();

    $('#calendar').fullCalendar({
        header: {
            left: 'prev,next today',
            center: 'title',
            right: 'month,agendaWeek,agendaDay'
        },
        defaultView: 'agendaDay',
        editable: true,
        events: [
        {
            id: 1,
            title: '<div class="fc-event-title">Meeting</div><div class="fc-sub-event">9am - 9:30am</div><div class="fc-sub-event">11:30am - 1pm</div><div class="fc-sub-event">1pm - 3pm</div>',
            start: new Date(y, m, d, 9, 0),
            end: new Date(y, m, d, 15, 0),
            allDay: false}
        ],
        eventRender: function(event, element, view) {
            element.find('.fc-event-content').html(element.find('.fc-event-content').text());
        },
        eventAfterRender: function(event, element, view) {
            var eleHgt = element.height()/4;
            $('.fc-sub-event').height(eleHgt);
        }
    });

});