jquery sortable board

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.12/jquery-ui.js"></script>
<div class='sequencer'>
  <ul id='sortableList'>
    <li>
      <img src='http://images.wikia.com/reddithistory/images/1/10/3-rage-face.png' />rage1</li>
    <li>
      <img src='http://images.wikia.com/reddithistory/images/1/10/3-rage-face.png' />rage2</li>
    <li>
      <img src='http://images.wikia.com/reddithistory/images/1/10/3-rage-face.png' />rage3</li>
    <li>
      <img src='http://images.wikia.com/reddithistory/images/1/10/3-rage-face.png' />rage4</li>
    <li>
      <img src='http://images.wikia.com/reddithistory/images/1/10/3-rage-face.png' />rage5</li>
          <li>
      <img src='http://images.wikia.com/reddithistory/images/1/10/3-rage-face.png' />rage5</li>
          <li>
      <img src='http://images.wikia.com/reddithistory/images/1/10/3-rage-face.png' />rage5</li>
          <li>
      <img src='http://images.wikia.com/reddithistory/images/1/10/3-rage-face.png' />rage5</li>
          <li>
      <img src='http://images.wikia.com/reddithistory/images/1/10/3-rage-face.png' />rage5</li>
      
  </ul>
</div>

CSS

.sequencer {
  height: 110px;
  width: 600px;
  overflow-y: hidden;
  overflow-x: hidden;
}
.sequencer ul {
  white-space: nowrap;
  overflow-x: scroll;
  overflow-y: hidden;
}
.sequencer li {
  display: inline-block;
  padding-right: 10px;
  padding-left: 10px;
  text-align: center;
}
.sequencer img {
  display: block;
  height: 50px;
}
.placeholder {
  background: #f3f3f3;
  visibility: visible;
}

JavaScript

$(document).ready(function() {
  $('#sortableList').sortable({
    refreshPositions: true,
    opacity: 0.6,
    scroll: true,
    containment: 'parent',
    placeholder: 'placeholder',
    tolerance: 'pointer',
    forcePlaceholderSize: true // <--- add this
  }).disableSelection();
});