What you're asking can't be done by reasonable means. You could use frames or iframes, but that's ugly and is no longer recognized as an acceptable solution.
What oldskool mentioned above is for CSS stylesheets, but they can't contain HTML.
In order to do what you want, you would need a serverside language that supports including other files, such as PHP.
PHP Code:
<?php
include ('menu.html');
// dynamic stuff here
?>