div.mainLinkContainerDiv { text-align: center; }
div.mainLink {
  margin: 0px auto;
  width: 210px;
  height: 100px;
}
div.mainLink:hover {
  -moz-opacity: 0.75;
  opacity: 0.75;
  filter: alpha(opacity=80);
  border: 1px solid blue;
  cursor: pointer;
}