jquery, Any short version to change top position relatively
<p>I want to add css top position relatively. 
if its top position is 30px, I want to add its position +30,
so its result is 60px. </p>

<p>so I have to do this like this,</p>

<pre><code>$("#btn").css("top", $("#btn").css("top")+30);
</code></pre>

<p>is there any shorter way or effecient way to do this.</p>
