Is it possible to change CSS Validation scheme in VS2010

I'm editing a simple CSS file in VS2010 and the editor seems to have a rather limited understanding of CSS, for example:

#my-rule {
     position:relative;
}

generates a warning: Validation(CSS 1.0): 'position' is not a known CSS property name

I'm guessing that there is an option some where to change the CSS validation to CSS 2.1 or some thing close, but can't for the life of me find it.