<span class="switcher switcher-1">
   <input type="checkbox" id="switcher-1">
   <label for="switcher-1"></label>
</span>
<span class="switcher switcher-2">
   <input type="checkbox" id="switcher-2">
   <label for="switcher-2"></label>
</span>

$black:#1E1E1E;
$grey:#CCCCCC;
$white:#FFFFFF;

body {
   display:flex;
   flex-direction:column;
   align-items:center;
   justify-content:center;
   
   height:100vh;
   
   background-color:$grey;
   span.switcher {
      position: relative;
      
      width:200px;
      height:50px;
      border-radius:25px;
      margin:20px 0;
      input {
         appearance: none;
         
         position: relative;

         width:200px;
         height:50px;
         border-radius:25px;

         background-color:$black;
         outline:none;

         font-family: 'Oswald', sans-serif;
         &:before, &:after {
            z-index:2;

            position: absolute;
            top:50%;
            transform:translateY(-50%);

            color:$white;
         }
         &:before {
            content: 'ON';
            left:20px;
         }
         &:after {
            content: 'OFF';
            right:20px;
         }
      }
      label {
         z-index:1;
         position: absolute;
         top:10px;
         bottom:10px;
         
         border-radius:20px;
      }
      &.switcher-1 {
         input {
            transition:.25s -.1s;
            &:checked {
               background-color:$white;
               &:before {
                  color:$white;
                  transition: color .5s .2s;
               }
               &:after {
                  color:$grey;
                  transition: color .5s;
               }
               &+label {
                  left:10px;
                  right:100px;

                  background:$black;
                  
                  transition: left .5s, right .4s .2s;
               }
            }
            &:not(:checked) {
               background:$black;
               transition: background .5s -.1s;
               &:before {
                  color:$grey;
                  transition: color .5s;
               }
               &:after {
                  color:$black;
                  transition: color .5s .2s;
               }
               &+label {
                  left:100px;
                  right:10px;
                  
                  background:$white;
                  
                  transition: left .4s .2s, right .5s, background .35s -.1s;
               }
            }
         }
      }
      &.switcher-2 {
         overflow:hidden;
         input {
               
            transition:background-color 0s .5s;
            &:before {
               color:$black;
            }
            &:after {
               color:$white;
            }
            &:checked {
               background-color:$white;
               &+label {
                  background:$white;
                  
                  animation: turn-on .5s ease-out;
                  
                  @keyframes turn-on {
                     0% {
                        left:100%;
                     }
                     100% {
                        left:0%;
                     }
                  }
               }
            }
            &:not(:checked) {
               background:$black;
               &+label {
                  background:$black;
                  
                  animation: turn-off .5s ease-out;
                  
                  @keyframes turn-off {
                     0% {
                        right:100%;
                     }
                     100% {
                        right:0%;
                     }
                  }
               }
            }
         }
         label {
            top:0px;
            
            width:200px;
            height:50px;
            border-radius:25px;
         }
      }
   }
}

/*
   https://dribbble.com/shots/4898152-Switcher-PRD
   But the colors are the correct way around on this pen, as I think a checkbox should say what it is - not what it will be when you click it
*/