body {
  font-family: "Arial";
  background-color: #e6e6e6;
  padding: 0;
  margin: 0;
}

nav {
  background-color: #000000;
  padding: 10px;
}

header {
  margin:10px;
}

main {
  margin:10px;
}

#skull {
  display: block;
  padding-top: 75px;
  padding-bottom:75px;
  margin-left: auto;
  margin-right: auto;
  animation: rotation 6s infinite linear;
}

footer {
  text-align: center;
}

@keyframes rotation {
  from {
    transform: rotate(0deg);
  }
  to {
    transform: rotate(359deg);
  }
}