.pendulum{position:absolute;left:50%;bottom:40%;transform:translateX(-50%)}.pendulum_box{display:flex;flex:1}.ball{height:40px;width:40px;border-radius:50%;background-color:#fff;position:relative;transform-origin:50% -300%}.ball.first{animation:firstball .9s ease-in infinite alternate}@keyframes firstball{0%{transform:rotate(35deg)}50%{transform:rotate(0deg)}}.ball.last{animation:lastball .9s ease-out infinite alternate}@keyframes lastball{50%{transform:rotate(0deg)}to{transform:rotate(-35deg)}}