* {
  box-sizing: border-box;
}
body {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100vw;
  height: 100vh;
  animation: backgroundFade 5s infinite;
}
#container {
  width: 100%;
  height: 100%;
  position: relative;
}
img {
  position: absolute;
  max-width: 300px;
  max-height: 300px;
  box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1);
  transition: opacity .3s ease-in-out;
}

@keyframes backgroundFade {
  0% { background-color: #e2be9f; }
  50% { background-color: #f7cecd; }
  100% { background-color: #e2be9f; }
}

.overlay-image {
  position: absolute;
  width: 100%; 
  height: 100%; 
  margin-top: 50%;
  margin-left: 50%;
}