body {
  background-color: #e8e8e8;
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100%;
  height: 90vh;
}

.newton-cradle {
  --uib-size: 50px;
  --uib-color: #474554;
  --uib-speed: 1.2s;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  width: var(--uib-size);
  height: var(--uib-size);
}

.newton-cradle__dot {
  position: relative;
  display: flex;
  align-items: center;
  height: 100%;
  width: 25%;
  transform-origin: center top;
}

.newton-cradle__dot::after {
  content: '';
  display: block;
  width: 100%;
  height: 25%;
  border-radius: 50%;
  background-color: var(--uib-color);
}

.newton-cradle__dot:first-child {
  animation: swing var(--uib-speed) linear infinite;
}

.newton-cradle__dot:last-child {
  animation: swing2 var(--uib-speed) linear infinite;
}

@keyframes swing {
  0% {
    transform: rotate(0deg);
    animation-timing-function: ease-out;
  }
  25% {
    transform: rotate(70deg);
    animation-timing-function: ease-in;
  }
  50% {
    transform: rotate(0deg);
    animation-timing-function: linear;
  }
}

@keyframes swing2 {
  0% {
    transform: rotate(0deg);
    animation-timing-function: linear;
  }
  50% {
    transform: rotate(0deg);
    animation-timing-function: ease-out;
  }
  75% {
    transform: rotate(-70deg);
    animation-timing-function: ease-in;
  }
}