body {
  background-image: linear-gradient(0, #FFFFFF 0%, #E5E5E5 80%);
}

.horizontal-stack {
  text-align: center;
}

#shelf {
  margin: auto;
}

#confluently {
  display: block;
  margin: 40px auto;
  background-image: url(../img/confluently.png);
  background-size: 100%;
  width: 252px;
  height: 320px;
}

#confluently:hover {
    background-position: bottom;
}

#quetie {
  display: block;
  margin: 80px auto;
  background-image: url(../img/quetie.png);
  background-size: 100%;
  width: 252px;
  height: 320px;
}

#quetie:hover {
    background-position: bottom;
}

@media screen and (min-width: 700px) {
  body {
    background-image: linear-gradient(0, #E5E5E5 0%, #E5E5E5 80%);
  }
  .horizontal-stack {
    display: flex;
    flex-direction: row;
    justify-content: space-around;
    align-items: center;
    text-align: center;
    margin: 0;
  }
  #shelf {
    margin: auto;
    margin-top: 60px;
    align-items: start;
    background-image: url(../img/table.png);
    background-size: 100%;
    width: 771px;
    height: 439px;
  }
  #confluently {
    margin: 0;
    background-image: url(../img/confluently.png);
  }
  #quetie {
    margin: 0;
    background-image: url(../img/quetie.png);
  }
}

.fadein {
  animation-name: fadein;
  animation-duration: 1s;
  animation-iteration-count: 1;
}

@keyframes fadein {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }