body {
  padding: 36px;
  text-align: center;
  font-family: monospace;
  font-size: 17px;
  color: #222;
  line-height: 1.45; 
}

#btn {
  cursor: pointer;
  width: 250px;
  text-align: center;
  padding: 6px 12px;
  font-size: 19px;
  display: inline-block;
}

@keyframes animate {
  
  from { 
    margin-top: 0; 
  }
  
  to   { 
    margin-top: 100px; 
  }
  
}

.wrapper {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
}

.block {
  background-color: red;
  padding: 36px 0;
  width: 175px;
  text-align: center;
  color: #fff;
  font-size: 15px;
  border: 2px solid rgba(255, 255, 255, .45);
  
  animation-name: animate;
  animation-duration: 1.25s;
  animation-iteration-count: infinite;
  animation-timing-function: ease-in;
  animation-delay: 0s;
  animation-direction: alternate;
  animation-play-state: paused;
}

.block-1 {
  animation-play-state: running;
}