#slideshow { 
  width: 855px; 
  height: 400px;
  position: relative; /* For IE */
  overflow: hidden;
  z-index: 30;
  margin: 100px 0 0 105px;
}

ul#slideshow_ul {
  width: 9999px;
  height: 400px;
  display: block;
  float: left;
  position: relative;
  z-index:30;
}

ul#slideshow_ul li {
  width: 855px;
  height: 400px;
  float: left;
  display: block;
}