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HTML 

              
                <div class="wrap">

  <section>
    <div class="input-wrap">
      <!-- Step 1 -->
      <!-- a checkbox input and label element -->
      <input id="input-1" type="checkbox">
      <label for="input-1">Select</label>
    </div>
  </section>

  <section>
    <div class="input-wrap">
      <input id="input-2" type="checkbox">
      <label for="input-2">Select</label>
    </div> 
  </section>


  <section>
    <div class="input-wrap">
      <input id="input-3" type="checkbox">
      <label for="input-3">Select</label>
    </div> 
  </section>

  <section>
    <div class="input-wrap">
      <input id="input-4" type="checkbox">
      <label for="input-4">Select</label>
    </div> 
  </section>

  <section>
    <div class="input-wrap">
      <input id="input-5" type="checkbox">
      <label for="input-5">Select</label>
    </div> 
  </section>

  <section>
    <div class="input-wrap">
      <input id="input-6" type="checkbox">
      <label for="input-6">Select</label>
    </div> 
  </section>

  <section>
    <div class="input-wrap">
      <input id="input-7" type="checkbox" checked>
      <label for="input-7">Select</label>
    </div> 
  </section>
  
</div>
!

CSS 

              
                section {
  &:nth-of-type(n) {
    // Step 1
    // a checkbox input and label element
    // see html
  }
  &:nth-of-type(n + 2) {
    // Step 2
    // start the label styling
    // with a white background
    label {
      display: inline-block;
      position: relative;
      height: 44px;
      width: 90px;
      background-color: #fff;
    }
  }
  &:nth-of-type(n+3) {
    // Step 3
    // round the corners,
    // hide the font
    // add mouse pointer on hover
    label {
      cursor: pointer;
      font-size: 0;
      color: transparent;
      border-radius: 22px;
    }
  }
  &:nth-of-type(n+4) {
    // Step 4
    // use an after pseudo element
    // to make the grey circle
    label:after {
      content: '';
      display: block;
      height: 40px;
      width: 40px;
      position: absolute;
      top: 2px;
      right: 48px;
      border-radius: 50%;
      background-color: #e8e8e8;
      box-shadow: 2px 0px 0px rgba(0,0,0,0.15);
    }
  }
  &:nth-of-type(n+5) {
    // Step 5
    // use the sibling selector
    // to style the label when
    // the input is checked
    input:checked + label {
      background: #ffd000;
    }
  }
  &:nth-of-type(n+6) {
    // Step 6
    // on input check also...
    // move the circle and
    // change shadow direction
    input:checked + label:after {
      right: 2px;
      background-color: #fff;
      box-shadow: -2px 0px 0px rgba(0,0,0,0.1);
    }
  }
  &:nth-of-type(n+7) {
    // Step 7
    // hide the input checkbox
    // keep visable for screen reader
    // then finally add transition to 
    // label and pseudo element
    input {
      position: absolute !important;
      width: 1px;
      height: 1px;
      overflow: hidden;
      clip: rect(0, 0, 0, 0);
      bottom: 0;
    }
    label {
      transition: background-color 500ms ease;
      &:after {
        transition: right 500ms ease, 
          background-color 500ms ease, 
          box-shadow 500ms ease;
      }
    }
  }
}











// Presentation styles

.wrap {
  display: flex;
  flex-wrap: wrap;
}

section {
  flex: 1;
  padding: 15px 0;
  text-align: center;
  
}

@for $i from 1 through 8 {
  section:nth-of-type(#{$i}) {
    background-color: darken(#eee, $i * 1.5);
   }
}

.input-wrap {
  position: relative;
  padding: 8px;
  min-width: 140px;
}

label {
  line-height: 44px;
  vertical-align: middle;
}
!

JS
!
999px

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