body {
  background-color: black;
  background-image: url('turtle.gif');
  background-repeat: repeat;
  font-family: "Courier New", monospace;
}

.nav-link {
  color: cyan;
  font-weight: bold;
  text-decoration: none;
  padding: 4px 8px;
}

.nav-link:hover {
  background-color: darkblue;
  color: yellow;
}