HTML has no way to recall something in particular for different pages unless it's put onto the pages by the coder or some programming is used. HTML is just markup, there's no conditional processing or programming logic to HTML that would know where to put the id=.
Here, take a look at this post about using includes for meta tags
You can have the styles for navigation that varies from section to section in a separate stylesheet, and "include" the proper one right after the tag including your global stylesheet.
>>first thing on the page, before even the DOCTYPE declaration, you would put:
$sectionstyle1="where the section 1 navigation styles are";
// Other variables you need for the page
Then you either use $sectionstyle1 with a PHP statement to include the proper stylesheet (just like you link to filename.css now, or print the section's styles as imbedded styles right into the <head> section of those pages.
However, I think it's getting mixed up here between CSS (for styling) and using includes (SSI or PHP) for the HTML in navigation for different sections (I am anyway). They're two different things.
I have a site now being re-worked for both CSS and with adding bits of PHP for automating a number of routine tasks, that has different "section" navigation for each of the different sections. Let's say one site section is seo and another is design. I just put this up and it works just fine.
Very first thing on the page - the HTML page itself, which still has its .html file extension, is
$sectionnav = "seoNav.php";
Then, exactly in the spot where I want that navigation to be I put
<?php include "$sectionnav";?>
The HTML code for the navigation, including id and class selectors, is in seoNav.php and gets put on the page server-side before it's ever delivered to a browser or a bot. The formatting for styling is done in the CSS. For the design section, it'll be "designNav.php" instead of "seoNav.php" - and I can't think of anything simpler. I don't think this can be done using SSI.
[edited by: Marcia at 7:10 am (utc) on Jan. 1, 2008]