unexplained validation error

Hello,

sorry to disturb You, but I have checked and fixed my site [ christ.eye-of-revelation.org ]
and I still found one error that I can't adjust:
  a.. #cf img.top:hover, #cf img.hover_effect  Parse Error opacity=0)
THE CODE IS:
  #cf img.top:hover, #cf img.hover_effect {
   opacity:0;
   filter: alpha(opacity=0);
   }
I have browsed the W3C page and see the same example there! could it deals with a bug somehow?

and a warning that is:
  a.. Warnings (9)
  URI : http://christ.eye-of-revelation.org/common.css
  102 Property -moz-border-radius is an unknown vendor extension
THE CODE IS:
   -moz-border-radius: 4px;
   -webkit-border-radius: 4px;
   border-radius: 4px;
   -moz-box-shadow: 0px 0px 4px #FaF5EF;
   -webkit-box-shadow: 0px 0px 4px #FaF5EF;
   box-shadow: 0px 0px 8px #FaF5EF;
   background-image: -moz-linear-gradient(top, #fdf8ff, #E1E4C0);
   background-image: -webkit-gradient(linear,left top,left bottom,color-stop(0, #fdf8ff),color-stop(1, #E4E1Bc));
   background-image: -webkit-linear-gradient(top, #fdf8ff, #E4E1Bc);
   background-image: -ms-linear-gradient(top,#fdf8ff, #E4E1Bc);
   background-image: -o-linear-gradient(top, #fdf8ff, #E4E1Bc);

They maybe unknown, but they work fine, and it was not easy to find the script. 
I attach the screenshots of the two cases: with and without these Properties, so that you can see the clear effect's difference.

So please, how can I embed the validation W3C certificate? it seems to be required for a page Audit.
And is this possible without making any icon appear into this special home page?

Thank you for your patience!

Kind Regards,
Antonio Alessi