<form>
  <div class="radiobtn">
    <input type="radio" id="huey"
           name="drone" value="huey" checked />
    <label for="huey">Huey</label>
  </div>

  <div class="radiobtn">
    <input type="radio" id="dewey"
           name="drone" value="dewey" />
    <label for="dewey">Dewey</label>
  </div>

  <div class="radiobtn">
    <input type="radio" id="louie"
           name="drone" value="louie" />
    <label for="louie">Louie</label>
  </div>

</form>

$accentcolor: #fcae2c;
$lightcolor: #fff;
$darkcolor: #444;

form {
  max-width: 250px;
  position: relative;
  margin: 50px auto 0;
  font-size: 15px;
}
.radiobtn {
  position: relative;
  display: block;
  label {
    display: block;
    background: lighten($accentcolor, 30%);
    color: $darkcolor;
    border-radius: 5px;
    padding: 10px 20px;
    border: 2px solid lighten($accentcolor, 20%);
    margin-bottom: 5px;
    cursor: pointer;
    &:after,
    &:before {
      content: "";
      position: absolute;
      right: 11px;
      top: 11px;
      width: 20px;
      height: 20px;
      border-radius: 3px;
      background: lighten($accentcolor, 15%);
    }
    &:before {
      background: transparent;
      transition: 0.1s width cubic-bezier(0.075, 0.82, 0.165, 1) 0s,
        0.3s height cubic-bezier(0.075, 0.82, 0.165, 2) 0.1s;
      z-index: 2;
      overflow: hidden;
      background-repeat: no-repeat;
      background-size: 13px;
      background-position: center;
      width: 0;
      height: 0;
      background-image: url(data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHZpZXdCb3g9IjAgMCAxNS4zIDEzLjIiPiAgPHBhdGggZmlsbD0iI2ZmZiIgZD0iTTE0LjcuOGwtLjQtLjRhMS43IDEuNyAwIDAgMC0yLjMuMUw1LjIgOC4yIDMgNi40YTEuNyAxLjcgMCAwIDAtMi4zLjFMLjQgN2ExLjcgMS43IDAgMCAwIC4xIDIuM2wzLjggMy41YTEuNyAxLjcgMCAwIDAgMi40LS4xTDE1IDMuMWExLjcgMS43IDAgMCAwLS4yLTIuM3oiIGRhdGEtbmFtZT0iUGZhZCA0Ii8+PC9zdmc+);
    }
  }
  input[type="radio"] {
    display: none;
    position: absolute;
    width: 100%;
    appearance: none;
    &:checked + label {
      background: lighten($accentcolor, 15%);
      animation-name: blink;
      animation-duration: 1s;
      border-color: $accentcolor;
      &:after {
        background: $accentcolor;
      }
      &:before {
        width: 20px;
        height: 20px;
      }
    }
  }
}

@keyframes blink {
  0% {
    background-color: lighten($accentcolor, 15%);
  }
  10% {
    background-color: lighten($accentcolor, 15%);
  }
  11% {
    background-color: lighten($accentcolor, 20%);
  }
  29% {
    background-color: lighten($accentcolor, 20%);
  }
  30% {
    background-color: lighten($accentcolor, 15%);
  }
  50% {
    background-color: lighten($accentcolor, 20%);
  }
  45% {
    background-color: lighten($accentcolor, 15%);
  }
  50% {
    background-color: lighten($accentcolor, 20%);
  }
  100% {
    background-color: lighten($accentcolor, 15%);
  }
}