.messages.custom_unsupportedsystem {
  display: none;
  position: relative;
}

.messages.custom_unsupportedsystem a.close {
  display: block;
  position: absolute;
  right: 12px;
  top: 12px;
  background: #840;
  color: #fff;
  font-size: 14px;
  line-height: 1;
  font-weight: bold;
  font-family: sans-serif;
  width: 20px;
  height: 20px;
}

.messages.custom_unsupportedsystem a.close:hover {
  text-decoration: none;
}

.messages.custom_unsupportedsystem a.close span {
  display: block;
  position: absolute;
  left: 0;
  top: 3px;
  width: 20px;
  height: auto;
  text-align: center;
}