body {
  height: 100vh;
  width: 100vw;
  display: flex;
  align-items: center;
  justify-content: center;
}

footer {
  position: absolute;
  bottom: 5px;
  right: 10px;
}
footer a:visited,
footer a:active,
footer a {
  text-decoration: none;
  color: blue;
}
footer a:visited:hover,
footer a:active:hover,
footer a:hover {
  text-decoration: underline;
}

#app {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
}