<ul class="list">
  <li class="list-item">
    <input type="checkbox" class="hidden-box" id="first" checked/>
    <label for="first" class="check--label">
      <span class="check--label-box"></span>
      <span class="check--label-text">First Checkbox</span>
    </label>
  </li>
  <li class="list-item">
    <input type="checkbox" class="hidden-box" id="second" />
    <label for="second" class="check--label">
      <span class="check--label-box"></span>
      <span class="check--label-text">Second Checkbox</span>
    </label>
  </li>
  <li class="list-item">
    <input type="checkbox" class="hidden-box" id="third" />
    <label for="third" class="check--label">
      <span class="check--label-box"></span>
      <span class="check--label-text">Third Checkbox</span>
    </label>
  </li>
</ul>

* {
  box-sizing: border-box;
}
html, body {
  display: flex;
  justify-content: center;
  align-items: center;
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  background-color: #1abc9c;
  font-family: 'Roboto', sans-serif;
}

.list {
  display: flex;
  flex-direction: column;
  margin: 0;
  padding: 0;
  width: 80%;
  max-width: 500px;
  background-color: #fff;
  border-radius: 6px;
  box-shadow: 10px 10px 0 0 rgba(0,0,0,0.2);
  list-style: none;
  overflow: hidden;
  
  .list-item {
    margin: 0;
    padding: 0;
    border-bottom: 1px solid #ecf0f1;
    position: relative;
    
    &:last-child {
      border: 0;
    }
  }
}

// hide the checkbox
.hidden-box {
  position: absolute;
  top: -9999px;
  left: -9999px;
  appearance: none;
  opacity: 0;
}

.check--label {
  font-size: 20px;
  margin: 0;
  display: flex;
  flex-direction: row;
  flex-wrap: nowrap;
  justify-content: flex-start;
  align-items: center;
}

.check--label-box {
  display: flex;
  align-self: center;
  position: relative;
  height: 20px;
  width: 20px;
  margin: 0 20px;
  border: 2px solid #3498db;
  border-radius: 2px;
  cursor: pointer;
}
.check--label-text {
  display: flex;
  align-self: center;
  position: relative;
  cursor: pointer;
  padding: 20px;
  border-left: 1px solid #ecf0f1;
  
  &:after {
    content: '';
    display: block;
    width: 0%;
    height: 2px;
    background-color: #000;
    position: absolute;
    top: 50%;
    left: 7.5%;
    transform: translateY(-50%);
    transition: width 100ms ease-in-out;
  }
}

// the magic
.hidden-box:checked + .check--label {
  background-color: #F9F9F9;
  .check--label-box {
    background-color: #3498db;
     &:after {
      content: '';
      display: block;
      position: absolute;
      top: -1px;
      left: 4px;
      width: 6px;
      height: 12px;
      border: solid #000;
      border-width: 0 2px 2px 0;
      transform: rotate(45deg);
    }
  }
  .check--label-text {
    &:after {
      width: 85%;
    }
  }
}