可拖动和可丢弃的z索引问题

我使用拖放jquery ui来创建表单输入，但z索引出现问题，因为拖动元素时元素在右侧div后面，但在拖放后它是可见的。那么，如何修复这个问题，使元素在拖动时在右侧div上可见

JSFIDDLE

在JS 中

$('#main1 div').draggable({
  cursor: 'pointer',
  connectWith: '.dropme2',
  helper: 'clone',
  zIndex: 10
});
$('.dropme2 form').sortable({
  connectWith: '.dropme',
  cursor: 'pointer',
  zIndex: 1000
});

HTML

<div class="dropme" id="main1">
  <div id="ytvid">YouTube video</div>
  <div id="paragraph">Paragraph</div>
</div>
<div class="dropme2" id="trash">
  <form id="form" style="width: 100%; min-height: 100px; float: left; padding-bottom: 40px; 
    position: relative; z-index: 2;">
    <input type="submit" id="getids" value="save" style="position: absolute; bottom: 0; left: 48%;" />
  </form>
</div>

CSS

#trash,
#main1 {
  display: inline-block;
  width: 250px;
  min-height: 100px;
  overflow: hidden;
  float: left;
  margin-right: 30px;
  background: rgb(236, 237, 240);
}
#trash {
  width: 300px;
  float: right;
  position: relative;
  z-index: 1;
}
#main1 {
  float: none;
  position: fixed;
  top: 30px;
  left: 30px;
  z-index: 9;
}
#main1 div {
  list-style: none;
  margin-bottom: 2px;
  background-color: #7F7F87;
  padding-left: 30px;
  width: 230px;
  cursor: -webkit-grab;
  color: #fff;
  font-size: 18px;
  height: 40px;
  line-height: 40px;
  float: left;
  position: relative;
  z-index: 10;
}
#trash form > div {
  height: auto;
  width: 97%;
  margin-bottom: 2px;
  background-color: #7F7F87;
  padding-left: 30px;
  cursor: -webkit-grab;
  color: #fff;
  font-size: 18px;
  line-height: 40px;
  position: relative;
  z-index: 10;
}
.highlight {
  padding: 5px;
  border: 2px dotted #fff09f;
  background: #fffef5;
}