Java api - Edit CSS on event in Jira edit form using datepicker

I would like to be able to change color of field when using datepicker to select date in edit form of Jira. I am having trouble unfortunately. Jira Core 7.6.2. Please help me understand what script can be used to achieve this goal.

image

//Way that I have gotten a date picker to work in jsfiddle
<script type="text/javascript">
$('document').ready(function() {
    $('#customfield_11000').datepicker()
        .on("input change", function () {
        $(this).css('background-color','red');
    });
});
</script>
<!--label, date field and datepicker icon html-->
<div class="field-group aui-field-datepicker">
    <label for="customfield_11000">Test choice 1</label>
    <input class="text medium-field datepicker-input" id="customfield_11000" name="customfield_11000" type="text" value="">
    <a href="#" id="customfield_11000-trigger" title="Select a date">
        <span class="icon-default aui-icon aui-icon-small aui-iconfont-calendar">Select a date</span>
    </a>
</div>
<!--actual date-picker html-->
<div class="calendar active" style="position: absolute; display: block; left: 692.891px; top: 78px;">
  <table cellspacing="0" cellpadding="0" style="visibility: visible;">
    <thead>
      <tr>
        <td colspan="1" class="button">
          <div unselectable="on">?</div>
        </td>
        <td colspan="6" class="title" style="cursor: move;">September, 2019</td>
        <td colspan="1" class="button">
          <div unselectable="on">×</div>
        </td>
      </tr>
      <tr class="headrow">
        <td colspan="1" class="button nav">
          <div unselectable="on">«</div>
        </td>
        <td colspan="1" class="button nav">
          <div unselectable="on">‹</div>
        </td>
        <td colspan="4" class="button">
          <div unselectable="on">Today</div>
        </td>
        <td colspan="1" class="button nav">
          <div unselectable="on">›</div>
        </td>
        <td colspan="1" class="button nav">
          <div unselectable="on">»</div>
        </td>
      </tr>
      <tr class="daynames">
        <td class="name wn">wk</td>
        <td class="name day weekend">Sun</td>
        <td class="day name">Mon</td>
        <td class="day name">Tue</td>
        <td class="day name">Wed</td>
        <td class="day name">Thu</td>
        <td class="day name">Fri</td>
        <td class="name day weekend">Sat</td>
      </tr>
    </thead>
    <tbody>
      <tr class="daysrow">
        <td class="day wn">36</td>
        <td class="day day-1 weekend">1</td>
        <td class="day day-2">2</td>
        <td class="day day-3">3</td>
        <td class="day day-4">4</td>
        <td class="day day-5">5</td>
        <td class="day day-6">6</td>
        <td class="day day-7 weekend">7</td>
      </tr>
      <tr class="daysrow">
        <td class="day wn">37</td>
        <td class="day day-8 weekend">8</td>
        <td class="day day-9">9</td>
        <td class="day day-10">10</td>
        <td class="day day-11">11</td>
        <td class="day day-12">12</td>
        <td class="day day-13">13</td>
        <td class="day day-14 weekend">14</td>
      </tr>
      <tr class="daysrow">
        <td class="day wn">38</td>
        <td class="day day-15 weekend">15</td>
        <td class="day day-16">16</td>
        <td class="day day-17">17</td>
        <td class="day day-18 selected today">18</td>
        <td class="day day-19">19</td>
        <td class="day day-20">20</td>
        <td class="day day-21 weekend">21</td>
      </tr>
      <tr class="daysrow">
        <td class="day wn">39</td>
        <td class="day day-22 weekend">22</td>
        <td class="day day-23">23</td>
        <td class="day day-24">24</td>
        <td class="day day-25">25</td>
        <td class="day day-26">26</td>
        <td class="day day-27">27</td>
        <td class="day day-28 weekend">28</td>
      </tr>
      <tr class="daysrow">
        <td class="day wn">40</td>
        <td class="day day-29 weekend">29</td>
        <td class="day day-30">30</td>
        <td class="emptycell">&nbsp;</td>
        <td class="emptycell">&nbsp;</td>
        <td class="emptycell">&nbsp;</td>
        <td class="emptycell">&nbsp;</td>
        <td class="emptycell">&nbsp;</td>
      </tr>
      <tr class="emptyrow">
        <td class="day wn">41</td>
        <td class="emptycell">&nbsp;</td>
        <td class="emptycell">&nbsp;</td>
        <td class="emptycell">&nbsp;</td>
        <td class="emptycell">&nbsp;</td>
        <td class="emptycell">&nbsp;</td>
        <td class="emptycell">&nbsp;</td>
        <td class="emptycell">&nbsp;</td>
      </tr>
    </tbody>
    <tfoot>
      <tr class="footrow">
        <td colspan="8" class="ttip" style="cursor: move;">Drag to move</td>
      </tr>
    </tfoot>
  </table>
  <div class="combo" style="display: none;">
    <div class="label">Jan</div>
    <div class="label">Feb</div>
    <div class="label">Mar</div>
    <div class="label">Apr</div>
    <div class="label">May</div>
    <div class="label">Jun</div>
    <div class="label">Jul</div>
    <div class="label">Aug</div>
    <div class="label">Sep</div>
    <div class="label">Oct</div>
    <div class="label">Nov</div>
    <div class="label">Dec</div>
  </div>
  <div class="combo" style="display: none;">
    <div class="label"></div>
    <div class="label"></div>
    <div class="label"></div>
    <div class="label"></div>
    <div class="label"></div>
    <div class="label"></div>
    <div class="label"></div>
    <div class="label"></div>
    <div class="label"></div>
    <div class="label"></div>
    <div class="label"></div>
    <div class="label"></div>
  </div>
</div>