Unable to display download button to the right inside a div - html

Question

Here is my html
<div id="under_post"> <!--START UNDER POST-->
<div id="post_info"> <!--START POST INFO-->
<p><span style="color: #000000;display: block;float: left;">Lorem ipsum dolor sit amet, consectetur adipiscing elit. In ut lectus sit amet quam gravida fermentum non a nibh. Praesent quam libero, dignissim vel luctus vel, sodales in justo</span></p>
</div> <!--END POST INFO-->
<div id="download_button"><!--START DOWNLOAD BUTTON -->
<a class="download" href="http://dl.dropbox.com/s/0iq6ik93rklbakh/Kirvy.zip">Download</a>
</div> <!--END DOWNLOAD BUTTON-->
</div>
css is as follows
#under_post {
margin: 0;
padding: 0;
width: 600px;
border: 1px solid black;
}
#post_info {
margin: 0;
padding: 0;
width: 400px;
}
div#download_button {
width: 100px;
}
div#download_button a.download {
display: block;
text-decoration: none;
color: white;
padding-top: 10px;
background-color: #e8432d;
width: 100px;
height: 30px;
text-align: center;
-moz-border-radius: 7px;
-webkit-border-radius: 7px;
border-radius: 7px;
-khtml-border-radius: 7px;
}
I want the download button to be aligned to right side under the #under_post div
Here's the link to the page I'm trying to get it to work on.
Link
Thanks in advance

Answer 1

Add float:left; to #under_post and #post_info
#under_post {
margin: 0;
padding: 0;
width: 600px;
border: 1px solid black;
float: left;
}
#post_info {
margin: 0;
padding: 0;
width: 400px;
float: left;
}
and add float:right;margin-top:25px; to div#download_button
div#download_button {
width: 100px;
float: right;
margin-top: 25px;
}
This is how it looks