Okay, I'm still working on my WordPress theme. The problem is, the default WordPress header.php has PHP code inserted such as:

HTML Code:
<link rel="stylesheet" href="<?php bloginfo('stylesheet_url'); ?>" type="text/css" media="screen" />
Now, I copied and pasted the code from the default header.php (minus the stuff between the <style</style> tags because I didn't need them) into my header.php file. When I ran my markup through the validator at W3C, the validator found no problems with my markup, except for the stuff in between the <head></head> tags. I tried to correct the errors which included escaping the < character i.e.

HTML Code:
<link rel="stylesheet" href="&lt;?php bloginfo('stylesheet_url'); ?>" type="text/css" media="screen" />
if the PHP was enclosed in "" like in the above example. Of course, in my browser, the CSS stylesheet refused to load even though the validator insisted that escaping these characters was the correct thing to do!

How do I get the validator to play nicely with WordPress?