overriding thickbox.css

I am using a child theme of TwentyTen and am trying to change the border around the nggallery single box display. Using the tools in Google Chrome I have determined that the correct place to make this change is in ‘includes/js/thickbox/thichkbox.css.

I make the change using the tools and everything works like I want it to – but if I try to override the ID in the child theme editor using the following:

#TB_window {
position: fixed;
background: #ffffff;
z-index: 102;
color:#000000;
visibility: hidden;
text-align:left;
top:50%;
left:50%;
border: 20px outset #1E4C02; <=== the change
-moz-box-shadow: rgba(0,0,0,1) 0 4px 30px;
-webkit-box-shadow: rgba(0,0,0,1) 0 4px 30px;
-khtml-box-shadow: rgba(0,0,0,1) 0 4px 30px;
box-shadow: rgba(0,0,0,1) 0 4px 30px;

it doesn’t work.

The page is at http://www.myprojectinfo.org/pilot. If you select ‘Phto Gallery’ and click on one of the thumbnails yow will see where I am trying to change the boder.

Any help will be appreciated.
}