This code should work add it at header in theme-layer.php , and please first try it on your demo website first , if your website have any type of damage i am not responsible ..
<style>#myaskbtn { position: fixed; bottom: 20px; left: 30px; z-index: 99; font-size: 24px; border: none; outline: none; cursor: pointer; padding: 5px; border-radius: 4px; } #myaskbtn:hover { background-color: #555; }</style><button type="button" id="myaskbtn" class="btn btn-warning btn-lg" data-toggle="modal" data-target="#myModal20"><i class="fa"></i>ASK</button>
<div class="modal fade" id="myModal20" role="dialog">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal">×</button>
<h4 class="modal-title">ASK YOUR QUESTION HERE</h4>
</div>
<div class="modal-body">
<form class="form-inline" method="post" action="<?php echo qa_path_html( 'ask' ); ?>">
<textarea STYLE="width:100%;height:250px;" type="text" id="ask" ></textarea>
<button type="submit" class="btn btn-primary">SUBMIT QUESTION</button> <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
<input type="hidden" name="doask1" value="1">
</form></div>
</div>
</div>
</div>