It's hard to get support for easy stuff.
I would recommend adding the CSS shadow to EXTRA.css and calling it in General Style Properties
e.g. put this in EXTRA.css
.MyShadow {
-webkit-box-shadow: 10px 10px 5px 0px rgba(0,0,0,0.75);
-moz-box-shadow: 10px 10px 5px 0px rgba(0,0,0,0.75);
box-shadow: 10px 10px 5px 0px rgba(0,0,0,0.75);
}