body {
  height: 100%; /* Ensure body and html take full height */
  margin: 0;
  padding: 0;
  background-color: black;
  color: white;
  outline: 1px;
  font-family: Verdana;
  background-image: url(images/stars1.gif);
}

.container {
display: flex;
justify-content: center;
align-items: center;
height: 100vh;
}

.myDiv {
  height: 100%;
  width: 40%;
  background-color: white;
  background-image: url(images/pattern592.gif);
  border-image: url(pulse.gif) 25% repeat;
}