error-notifier {
  position: fixed;
  z-index: 2000;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;  
  justify-content: center;
  align-items: center;
  background-color: rgba(0, 0, 0, 0.75);
  display: none;
}

error-notifier[open] {
  display: flex;
}