Please help with floating divs?

I am having trouble with floating divs. I am very tired and know i'm just forgetting something here is what I have.

my CSS

div#main {
text-align: left;
margin-top: 1px;
padding: 10px;
}

#content {
  margin-right:  175px;
}
#rightnav {
  float: right;
  width: 150px;
}

Code (markup):

and here is the code:

<div id="main">
<div id="content"><?php include('body.php');?></div>
<div id="rightnav"><?php include('rightnav.php');?></div>
</div>

Code (markup):

What is happening is the content is showing up top left and the rightnav is showing up bottom right. Anyone see what i'm doing wrong?

Thank you in advance

 

Try this

#content {
  margin-right:  175px;
  float: left;
}
#rightnav {
  float: left;
  width: 150px;
}

Code (markup):

 

Thank you for your reply. I tried that and it just puts the content left aligned and the rightnav left aligned below it. any other thoughts?

 

perhaps the problem is in your <?php include('body.php');?> and <?php include('rightnav.php');?>

 

those to files only have text in them for the time being so that I can test the 2 columns. There is no code in either of them. I'm at a loss