At the moment, no, you can’t use the document ID as part of the path to the CSS document. For instance, if I had a CSS document with an alias of sitestyle.css and a document ID of 35, this wouldn’t work:
<style type="text/css" media="all">
@import url('[(site_url)][~35~]');
</style>
The reason is that the parsed code would turn into this:
<style type="text/css" media="all">
@import url('http://www.mysite.com/sitestyle.css.html');
</style>
The problem is the .html at the end. Although alot of browsers will still work with this, Internet Explorer won’t and thus your CSS code isn’t used. The only way to get Internet Explorer to work is to not have an .html extension...just a .css extension. Thus, something like this would work:
<style type="text/css" media="all">
@import url('[(site_url)]sitestyle.css');
</style>
The other links provided in this thread go over the issue a bit more in detail.