#siteMessage {
  height: 100%;
  width: 100%;
  background-color: rgb(122,122,122,.8);
  position: absolute;
  top: 0px;
  bottom: 0px;
}
#siteMessage > div {
  position: absolute;
  background-color: white;
  width: 15em;
  border: 3px outset black;
  border-radius: 1em;
  top: calc(50vh - 1em);
  right: calc(50% - 7.5em);
  padding: .2em;
}
#siteMessage > div > a {
  display: block;
  clear: both;
  padding: 5px;
  color: red;
}