* {
  padding: 0px 0px;
  margin: 0px 0px;
}
html,
body {
  padding: 0;
  margin: 0;
  width: 100%;
  height: 100%;
}
body {
  display: flex;
  justify-content: center;
  align-items: center;
}
body img {
  width: 30em;
  height: 30em;
}

@media screen and (max-width: 500px) {
  body img {
    width: 20em;
    height: 20em;
  }
}