Topic: How to specifically position flash object

I cannot for the life of me control the position of the Simpleviewer Flash object.  THis code will not work:

    #show {
    display: block;
    position: relative;
    left: 50px;
    top: 100px;
    border: 1px solid;

I want to specifically position this, or at the very least put it in the center of the window.