Datatables FixedHeader Defect

HTML

<script src="//code.jquery.com/jquery-1.12.0.min.js"></script>
<script src="https://cdn.datatables.net/1.10.11/js/jquery.dataTables.min.js"></script>
<link rel="stylesheet" href="https://cdn.datatables.net/1.10.11/css/jquery.dataTables.min.css">
<script src="https://cdn.datatables.net/fixedheader/3.1.1/js/dataTables.fixedHeader.min.js"></script>
<link rel="stylesheet" href="https://cdn.datatables.net/fixedheader/3.1.1/css/fixedHeader.dataTables.min.css">
<table id="example" class="display" cellspacing="0" width="100%">
        <thead>
            <tr>
                <th>1</th>
                <th colspan="2">2 & 3</th>
                <th>4</th>
                <th>5</th>
                <th>6</th>
            </tr>
            <tr>
                <th>Name</th>
                <th>Position</th>
                <th>Office</th>
                <th>Age</th>
                <th>Start<br/></br/>date</th>
                <th>Salary</th>
            </tr>
        </thead>
 
        <tbody>
            <tr>
                <td>Tiger Nixon</td>
                <td>System Architect</td>
                <td>Edinburgh</td>
                <td>61</td>
                <td>2011/04/25</td>
                <td>$320,800</td>
            </tr>
            <tr>
                <td>Garrett Winters</td>
                <td>Accountant</td>
                <td>Tokyo</td>
                <td>63</td>
                <td>2011/07/25</td>
                <td>$170,750</td>
            </tr>
            <tr>
                <td>Ashton Cox</td>
                <td>Junior Technical Author</td>
                <td>San Francisco</td>
                <td>66</td>
                <td>2009/01/12</td>
                <td>$86,000</td>
            </tr>
            <tr>
                <td>Cedric Kelly</td>
                <td>Senior Javascript Developer</td>
                <td>Edinburgh</td>
                <td>22</td>
                <td>2012/03/29</td>
                <td>$433,060</td>
           ...

CSS

/* Code provided by tonyiecla here: https://datatables.net/forums/discussion/comment/158277/#Comment_158277 */
.fixedHeader-floating>thead>tr>th {
  /* Solves the issue, but causes a th height mismatch for multi-line th
  display: inline-block !important;
  */
}

th {  
  line-height: 0.7;
}
th, td {  
  border: 1px solid;
}

JavaScript

$(document).ready(function() {
  $('#example').DataTable({
    fixedHeader: true,
    paging: false,
  });
});