<div class="container">
  <fieldset id="c-group">
    <label for="c1">
      <input type="checkbox" id="c1" name="c-group" checked>
      <span class="label-text">cats are good</span>
    </label>
    <label for="c2">
      <input type="checkbox" id="c2" name="c-group">
      <span class="label-text">cats are the best</span>
    </label>
    <label for="c3">
      <input type="checkbox" id="c3" name="c-group">
      <span class="label-text">i love cats</span>
    </label>
    <label for="c4">
      <input type="checkbox" id="c4" name="c-group" disabled>
      <span class="label-text">i want to pet all the cats <span class="aside">(checkbox disabled)</span></span>
    </label>
    <label for="c5">
      <input type="checkbox" id="c5" name="c-group" disabled checked>
      <span class="label-text">cats are nice <span class="aside">(checkbox checked + disabled)</span></span>
    </label>
  </fieldset>
  <fieldset id="r-group">
    <label for="r1">
      <input type="radio" id="r1" name="r-group">
      <span class="label-text">dogs are good</span>
    </label>
    <label for="r2">
      <input type="radio" id="r2" name="r-group">
      <span class="label-text">dogs are the best</span>
    </label>
    <label for="r3">
      <input type="radio" id="r3" name="r-group">
      <span class="label-text">i love dogs</span>
    </label>
    <label for="r4">
      <input type="radio" id="r4" name="r-group" disabled>
      <span class="label-text">i want to pet all the dogs <span class="aside">(radio disabled)</span></span>
    </label>
    <label for="r5">
      <input type="radio" id="r5" name="r-group" disabled checked>
      <span class="label-text">dogs are nice <span class="aside">(radio checked + disabled)</span></span>
    </label>
  </fieldset>
  <fieldset id="c-group-filled">
    <label for="cf1">
      <input type="checkbox" id="cf1" name="c-group-filled" class="filled" checked>
      <span class="label-text">cats are good</span>
    </label>
    <label for="cf2">
      <input type="checkbox" id="cf2" name="c-group-filled" class="filled">
      <span class="label-text">cats are the best</span>
    </label>
    <label for="cf3">
      <input type="checkbox" id="cf3" name="c-group-filled" class="filled">
      <span class="label-text">i love cats</span>
    </label>
    <label for="cf4">
      <input type="checkbox" id="cf4" name="c-group-filled" class="filled" disabled>
      <span class="label-text">i want to pet all the cats <span class="aside">(checkbox disabled)</span></span>
    </label>
    <label for="cf5">
      <input type="checkbox" id="cf4" name="c-group-filled" class="filled" disabled checked>
      <span class="label-text">cats are nice <span class="aside">(checkbox checked + disabled)</span></span>
    </label>
  </fieldset>
  
</div>

// radios
@checkbox-size: 16px;
@margin: 16px;
@margin-small: @margin / 2;
@text-lighter: #ccc;
@brand: #12CBC4;

body {
  font-family: sans-serif;
  color: #444;
  box-sizing: border-box;
}

.container {
  display: flex;
  flex-direction: column;
  width: 100vw;
  align-items: center;
  margin: 30px;
}

fieldset {
  border: none;
  display: flex;
  flex-direction: column;
  margin: 20px;
  align-items: flex-start;
  min-width: 400px;
}

label {
  display: flex;
  flex-direction: row;
  align-items: center;
}

.aside {
  color: @text-lighter;
}

input {
  position: relative !important;
  appearance: none;
  margin: @margin-small;
  box-sizing: content-box;
  overflow: hidden;

  // circle
  &:before {
    content: '';
    display: block;
    box-sizing: content-box;
    width: @checkbox-size;
    height: @checkbox-size;
    border: 2px solid @text-lighter;
    transition: 0.2s border-color ease;
  }
  
  &:checked:before {
    border-color: @brand;
    transition: 0.5s border-color ease;
  }
  
  &:disabled:before {
    border-color: @text-lighter;
    background-color: @text-lighter;
  }

  // dot
  &:after {
    content: '';
    display: block;
    position: absolute;
    box-sizing: content-box;
    top: 50%;
    left: 50%;
    transform-origin: 50% 50%;
    background-color: @brand;
    width: @checkbox-size;
    height: @checkbox-size;
    border-radius: 100vh;
    transform: translate(-50%, -50%) scale(0);
  }

  &[type="radio"] {
    &:before {
      border-radius: 100vh;
    }

    &:after {
      width: @checkbox-size;
      height: @checkbox-size;
      border-radius: 100vh;
      transform: translate(-50%, -50%) scale(0);
    }

    &:checked:after {
      animation: toggleOnRadio 0.2s ease forwards;
    }
  }

  &[type="checkbox"] {
    &:before {
      border-radius: @checkbox-size / 4;
    }

    &:after {
      width: @checkbox-size * 0.6;
      height: @checkbox-size;
      border-radius: 0;
      transform: translate(-50%, -85%) scale(0) rotate(45deg);
      background-color: transparent;
      box-shadow: 4px 4px 0px 0px @brand;
    }

    &:checked:after {
      animation: toggleOnCheckbox 0.2s ease forwards;
    }
  }
  
  &[type="checkbox"].filled  {
    &:before {
      border-radius: @checkbox-size / 4;
      transition: 0.2s border-color ease, 0.2s background-color ease;
    }
    
    &:checked:not(:disabled):before {
      background-color: @brand;
    }

    &:not(:disabled):after {
      box-shadow: 4px 4px 0px 0px white;
    }
  }
}

@keyframes toggleOnCheckbox {
  0% {
    opacity: 0;
    transform: translate(-50%, -85%) scale(0) rotate(45deg);
  }

  70% {
    opacity: 1;
    transform: translate(-50%, -85%) scale(0.9) rotate(45deg);
  }
  
  100% {
    transform: translate(-50%, -85%) scale(0.8) rotate(45deg);
  }
}

@keyframes toggleOnRadio {
  0% {
    opacity: 0;
    transform: translate(-50%, -50%) scale(0);
  }

  70% {
    opacity: 1;
    transform: translate(-50%, -50%) scale(0.9);
  }
  
  100% {
    transform: translate(-50%, -50%) scale(0.8);
  }
}