<input type="checkbox" id="toggle" name="toggle" value="is_on">
<label for="toggle" class="toy-toggle">
  <span class="border1"></span>
  <span class="border2"></span>
  <span class="border3"></span>
  <span class="handle">
    <span class="handle-off"></span>
    <span class="handle-on"></span>
  </span>
</label>

*, *:before, *:after {
  border: 0;
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
body {
  background: linear-gradient(#fff,#ccc);
  display: flex;
  height: 100vh;
  --on: #88e661;
  --off: #f0f0f0;
  --transDur: 0.6s;
}
input {
  position: fixed;
  transform: translateX(-100%);
}
.toy-toggle {
  background:
    radial-gradient(at top left,#fff 10%,#fff0 20%),
    radial-gradient(at top right,#fff 20%,#e4e4e4 35%);
  border-radius: 6em;
  box-shadow:
    0 0 0.25em #0002,
    0 3em 1.5em 0.5em #0002;
  cursor: pointer;
  display: block;
  font-size: 12px;
  position: relative;
  margin: auto;
  width: 20em;
  height: 12em;
  -webkit-tap-highlight-color: transparent;
}
.toy-toggle span {
  display: block;
  position: absolute;
}
.toy-toggle > span {
  top: 50%;
  left: 50%;
}
.toy-toggle > span:not(.handle) {
  transform: translate(-50%,-50%);
}
.border1 {
  background: #f0f0f0;
  border-radius: 5.5em;
  box-shadow: 0 0 0.2em 0.1em #f0f0f0;
  width: 19em;
  height: 11em;
}
.border2 {
  background: linear-gradient(0deg,#fff 33%,#ccc 45%);
  border-radius: 4.75em;
  box-shadow: 0 0 0.2em 0.3em #f0f0f0 inset;
  width: 16.5em;
  height: 9.5em;
}
.border3, .handle {
  background: linear-gradient(90deg, var(--on) 50%, var(--off) 0);
}
.border3 {
  background-position: 75% 0;
  background-size: 200% 100%;
  border-radius: 4.25em;
  box-shadow:
    0 0 0.1em 0.1em #ddd inset,
    0 1.5em 1.5em 1em #0004 inset,
    0 0 0 4.25em #0002 inset;
  width: 15.5em;
  height: 8.5em;
  transition: background-position var(--transDur) ease-in-out;
}
.handle {
  border-radius: 50%;
  box-shadow: 0 0 0.5em 0 #0007;
  width: 8.5em;
  height: 8.5em;
  transform: translate(-90%,-50%);
  transition: transform var(--transDur) ease-in-out;
  z-index: 0;
}
.handle:before {
  background:
    radial-gradient(2em 1.5em at 50% 35%,#fff6 15%,#fff0),
    radial-gradient(1.5em 2.5em at 75% 40%,#fff6 15%,#fff0),
    radial-gradient(100% 100% at 50% 33%,#0000 25%,#0003 50%);
  border-radius: 50%;
  box-shadow: 0 0 0.3em 0.1em #0003 inset;
  content: "";
  display: block;
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 3;
}
.handle-off, .handle-on {
  width: 50%;
  height: 100%;
  transition: transform calc(var(--transDur)/2);
  z-index: 2;
}
.handle-off {
  background: var(--off);
  border-radius: 100% 0 0 100% / 50% 50% 50% 50%;
  right: 50%;
  transform-origin: 100% 50%;
  transition-delay: calc(var(--transDur)/2);
  transition-timing-function: ease-out;
}
.handle-on {
  background: var(--on);
  border-radius: 0 100% 100% 0 / 50% 50% 50% 50%;
  left: 50%;
  transform: scaleX(0);
  transform-origin: 0 50%;
  transition-timing-function: ease-in;
}

/* On */
input:checked + .toy-toggle .border3 {
  background-position: 25% 0;
}
input:checked + .toy-toggle .handle {
  transform: translate(-10%,-50%);
}
input:checked + .toy-toggle .handle-off {
  transform: scaleX(0);
  transition-delay: 0s;
  transition-timing-function: ease-in;
}
input:checked + .toy-toggle .handle-on {
  transform: scaleX(1);
  transition-delay: calc(var(--transDur)/2);
  transition-timing-function: ease-out;
}