<div class="toggle">
  <input type="checkbox" class="check">
  <b class="b switch"></b>
  <b class="b track"></b>
</div>

* {
  margin: 0;
  padding: 0;
  position: relative;
  box-sizing: border-box;
}

html, body {
  height: 100%;
}

.b {
  display: block;
}

.toggle {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 60px;
  height: 40px;
  border-radius: 100px;
  background-color: #ddd;
  margin: -20px -40px;
  overflow: hidden;
  box-shadow: inset 0 0 2px 1px rgba(0,0,0,.05);
}

.check {
  position: absolute;
  display: block;
  cursor: pointer;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  z-index: 6;
}

  .check:checked ~ .track {
    box-shadow: inset 0 0 0 20px #4bd863;
  }

  .check:checked ~ .switch {
    right: 2px;
    left: 22px;
    transition: .35s cubic-bezier(0.785, 0.135, 0.150, 0.860);
    transition-property: left, right;
    transition-delay: .05s, 0s;
  }

.switch {
  position: absolute;
  left: 2px;
  top: 2px;
  bottom: 2px;
  right: 22px;
  background-color: #fff;
  border-radius: 36px;
  z-index: 1;
  transition: .35s cubic-bezier(0.785, 0.135, 0.150, 0.860);
  transition-property: left, right;
  transition-delay: 0s, .05s;
  box-shadow: 0 1px 2px rgba(0,0,0,.2);
}

.track {
  position: absolute;
  left: 0;
  top: 0;
  right: 0;
  bottom: 0;
  transition: .35s cubic-bezier(0.785, 0.135, 0.150, 0.860);
  box-shadow: inset 0 0 0 2px rgba(0,0,0,.05);
  border-radius: 40px;
}