css3 3d transforms (cf. css transform on MDN and this tutorial) may help you. basically, you have to display two nested elements, one of which represents your shadow while the othe has your content.
define some offset for the inner element and apply a suitable 3d transform to the outer element.
basically your transform clause would look like this:
transform: skewX(-5deg) skewY(-10deg) perspective( 600px ) rotateY( 45deg ) ;
here you have a live example.
there are a couple of aspects to consider:
you have to resort to 3d transforms to achieve the desired distortion effect from a 2d layer perpendicular to the normal of the 2d screen.
some of the transforms need vendor prefixes.
the transforms might not work across all user agents. the example has been tested on chrome 33 ( chrome 33.0.1750.154 ).
the css shadow seem to not be subjected to the perspective transforms - therefore you'd need the nested structure. on platforms where these transforms were applied to the css adornments too, you'd save the nesting of elements.