@keyframes btn {
   50% {transform: rotate(0deg);}
   25% {transform: rotate(30deg);}
   75% {transform: rotate(-30deg);}
}
body {
  background: #78e
}


#click {
   animation: btn 10s infinite linear;
   padding: 20px;
}
.container {
   height: 80vh;
   display: flex;
   justify-content: center;
   align-items: center;
}
.hidden{
   display: none;
}