html,
body {
  margin: 0;
  min-height: 100%;
  background: #111;
}

body {
  display: flex;
  justify-content: center;
}

.placeholder {
  width: 100%;
  max-width: 1600px;
}

.placeholder img {
  display: block;
  width: 100%;
  height: auto;
}