[jQuery] Thickbox Fixed Position?

[blemming]

Is it possible to fix the position of the thickbox? I have a client
that wants the thickbox exactly 115px off the top regardless of the
scrollbar position.  I tried to adjust the following css but I had
different results depending on the size of the thickbox. The problem
is that we have 3 different size thickbox implementations but they all
need to be fixed to the same position of top:115px;

#TB_window {
  position: fixed;
  background: url(img/popin_bg.jpg) top repeat-x #FFFFFF;
  z-index: 102;
  color:#000000;
  display:none;
  border: 5px solid #ff9900;
  text-align:left;
  top:50%; <= I set that to a fixed size of 115px......
  left:50%;
}

Any thoughts would be greatly appreciated.

Best, David