RE: How does the svg element handle CSS border and background-color?

Those properties are not applicable to SVG elements. See the list of CSS properties that can be applied to SVG elements here: http://www.w3.org/TR/2010/WD-SVG11-20100622/styling.html#SVGStylingProperties

 
That is what I thought.  However, the problem area is putting the svg tag inside an html5 document.  You can then apply background-color, borders, etc....
Several questions:
* Should the HTML5 spec forbid applying non-svg properties to the svg element when embedded in an html5 document?  (I'm not sure if this would work though)
 
* Should the CSS properties be allowed, but with special conditions?