Minor styling problem in UCP, etc.

Simply check out the UCP... the bottom corners in prosilver style don't fit. That's because they use the same style as the corners on top.
Here's the "guilty" code for your references from colours.css:

#cp-main span.corners-bottom, #cp-menu span.corners-bottom {
background-image: url("

{T_THEME_PATH}/images/corners_left2.gif");
}

#cp-main span.corners-bottom span, #cp-menu span.corners-bottom span {
background-image: url("{T_THEME_PATH}

/images/corners_right2.gif");
}