body {
  --duration: 0.3s;

  display: flex;
  justify-content: center;
  align-items: center;

  height: 100vh;
  width: 100vw;

  margin: 0;
  padding: 0;

  font-family: Arial, "Helvetica Neue", Helvetica, sans-serif;
}

.checkbox {
  display: flex;
  align-items: center;

  margin: 1rem;
}
.checkbox input {
  display: none;
}
.checkbox label {
  --size: 1.5rem;
  display: flex;
  align-items: center;

  height: var(--size);
  width: calc(var(--size) * 2);

  background-color: #dfe4ea;
  border-radius: var(--size);
  margin-right: 0.5rem;

  transition: background-color var(--duration);
}

.checkbox label .ball {
  --span-size: 0.2rem;
  --ball-size: calc(var(--size) - (var(--span-size) * 2));

  position: relative;
  left: var(--span-size);

  height: var(--ball-size);
  width: var(--ball-size);
  background-color: white;
  border-radius: 50%;

  transition: left var(--duration) linear;
  animation: enlarge1 var(--duration) linear forwards;
}

.checkbox input:checked + label {
  background-color: #2ed573;
}
.checkbox input:checked + label .ball {
  left: calc(100% - (var(--ball-size) + var(--span-size)));
  animation: enlarge var(--duration) linear forwards;
}
@keyframes enlarge {
  50% {
    transform: scale(1.2);
  }
}
@keyframes enlarge1 {
  50% {
    transform: scale(1.2);
  }
}