html, body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  background: black;
  color: #33ccff;
  font-family: Arial, sans-serif;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

h1 {
  font-weight: normal;
  margin: 0 0 20px;
}

img {
  display: block;
  max-width: 90vw;     /* maximal 90 % der Bildschirmbreite */
  max-height: 70vh;    /* maximal 70 % der Bildschirmhöhe */
  height: auto;
  width: auto;
  background: black;
}

a {
  color: #3366ff;
  text-decoration: none;
  margin-top: 20px;
}