div 缓慢消失

<div class="alt" id="pane">
<div id="mainf">
<div id="clp">
<span style="height:50px; line-height:50px;">点击图片消失</span>
</div>
</div>

</div>

<script type="text/javascript">
$(document).ready(function() {
$("#pane").click(function() {
$(this).animate({
opacity : "hide"
}, "slow");
});


});

</script>