body {
  background-color: #26292C;
}
img {
  max-width:100%;
  -webkit-filter: drop-shadow(1px 1px 0 black)
  drop-shadow(-1px -1px 0 black);
  filter: drop-shadow(1px 1px 0 black)
  drop-shadow(-1px -1px 0 black);
}

.centered {
  position: fixed;
  top: 50%;
  left: 50%;
  /* bring your own prefixes */
  transform: translate(-50%, -50%);
}