Vbulletin does not wrap quotes around it's embedded styles.
Example:
PHP Code:
<!-- CSS Stylesheet -->
<style type="text/css" id="vbulletin_css">
/**
* vBulletin 3.8.3 CSS
...
*/
etc.
Vbulletin should add html comments around these style definitions.
Because the comments are not added, my pages do not validate in a html validator (I use an expression in the style that gives me the error "character '<' is the first character of a delimiter but occurred as data").