div.image_overlay
{
 position: fixed;
 top: 0px;
 left: 0px;
 width: 100%;
 height: 100%;
 background-color: rgba(200, 200, 200, 0.5);
 z-index: 500;
 overflow: auto;
 text-align:center;
}

table.image_overlay_holder
{
}

img.overlay_image
{
 left:0;
 right:0;
 position: absolute;
 margin-left:auto;
 margin-right:auto;
 top: 40px;
}

canvas.overlay_canvas
{
 position: absolute;
 left:0;
 right:0;
 margin-left:auto;
 margin-right:auto;
 top: 34px;
}