mdb-ui-kit/sass/_checkboxes.scss

.form-horizontal .checkbox {
  padding-top: 20px;
}
.checkbox {
  transform: translateZ(0); // Force 3d rendering
  label {
    cursor: pointer;
    padding-left: 0; // Reset for Bootstrap rule
  }

  // Hide native checkbox
  input[type=checkbox] {
    opacity: 0;
    position: absolute;
    margin: 0;
    z-index: -1;
    width: 0;
    height: 0;
    overflow: hidden;
    left: 0;
    pointer-events: none;
  }

  .checkbox-material {
    vertical-align: middle;
    position: relative;
    top: 3px;
    &:before {
      display: block;
      position: absolute;
      left: 0;
      content: "";
      background-color: rgba(0,0,0,.84);
      height: $checkbox-size;
      width: $checkbox-size;
      border-radius: 100%;
      z-index: 1;
      opacity: 0;
      margin: 0;
      transform: scale3d(2.3, 2.3, 1);
    }

    .check {
      position: relative;
      display: inline-block;
      width: $checkbox-size;
      height: $checkbox-size;
      border: 2px solid;
      border-radius: 2px;
      overflow: hidden;
      z-index: 1;
    }
    .check:before {
      position: absolute;
      content: "";
      transform: rotate(45deg);
      display: block;
      margin-top: -4px;
      margin-left: 6px;
      width: 0;
      height: 0;
      box-shadow:
        0 0 0 0,
        0 0 0 0,
        0 0 0 0,
        0 0 0 0,
        0 0 0 0,
        0 0 0 0,
        0 0 0 0 inset;
      animation: checkbox-off $checkbox-animation-check forwards;
    }
  }

  input[type=checkbox]:focus + .checkbox-material .check:after {
    opacity: 0.2;
  }
  input[type=checkbox]:checked + .checkbox-material .check:before {
    box-shadow:
      0 0 0 10px,
      10px -10px 0 10px,
      32px 0px 0 20px,
      0px 32px 0 20px,
      -5px 5px 0 10px,
      20px -12px 0 11px;
    animation: checkbox-on $checkbox-animation-check forwards;
  }

  input[type=checkbox]:not(:checked) + .checkbox-material:before {
    animation: rippleOff $checkbox-animation-ripple;
  }
  input[type=checkbox]:checked + .checkbox-material:before {
    animation: rippleOn $checkbox-animation-ripple;
  }

  // Ripple effect on click
  input[type=checkbox]:not(:checked) + .checkbox-material .check:after {
    animation: rippleOff $checkbox-animation-ripple forwards;
  }
  input[type=checkbox]:checked + .checkbox-material .check:after {
    animation: rippleOn $checkbox-animation-ripple forwards;
  }

  // Style for disabled inputs
  input[type=checkbox][disabled]:not(:checked) ~ .checkbox-material .check:before,
  input[type=checkbox][disabled] + .circle {
    opacity: 0.5;
  }
  input[type=checkbox][disabled] + .checkbox-material .check:after {
    background-color: $lightbg-text;
    transform: rotate(-45deg);
  }

  @include variations(unquote(" input[type=checkbox]:checked + .checkbox-material .check:after"), background-color, $success);
  @include variations(unquote(" input[type=checkbox]:checked + .checkbox-material .check:before"), color, #4caf50);
  @include variations(unquote(" input[type=checkbox]:checked + .checkbox-material .check"), color, #4caf50);
}


@keyframes checkbox-on {
  0% {
    box-shadow:
      0 0 0 10px,
      10px -10px 0 10px,
      32px 0px 0 20px,
      0px 32px 0 20px,
      -5px 5px 0 10px,
      15px 2px 0 11px;
  }
  50% {
    box-shadow:
      0 0 0 10px,
      10px -10px 0 10px,
      32px 0px 0 20px,
      0px 32px 0 20px,
      -5px 5px 0 10px,
      20px 2px 0 11px;
  }
  100% {
    box-shadow:
      0 0 0 10px,
      10px -10px 0 10px,
      32px 0px 0 20px,
      0px 32px 0 20px,
      -5px 5px 0 10px,
      20px -12px 0 11px;
  }
}
@keyframes checkbox-off {
  0% {
    box-shadow:
      0 0 0 10px,
      10px -10px 0 10px,
      32px 0px 0 20px,
      0px 32px 0 20px,
      -5px 5px 0 10px,
      20px -12px 0 11px,
      0 0 0 0 inset;
  }

  25% {
    box-shadow:
      0 0 0 10px,
      10px -10px 0 10px,
      32px 0px 0 20px,
      0px 32px 0 20px,
      -5px 5px 0 10px,
      20px -12px 0 11px,
      0 0 0 0 inset;
  }
  50% {
    transform: rotate(45deg);
    margin-top: -4px;
    margin-left: 6px;
    width: 0px;
    height: 0px;
    box-shadow:
      0 0 0 10px,
      10px -10px 0 10px,
      32px 0px 0 20px,
      0px 32px 0 20px,
      -5px 5px 0 10px,
      15px 2px 0 11px,
      0 0 0 0 inset;
  }
  51% {
    transform: rotate(0deg);
    margin-top: -2px;
    margin-left: -2px;
    width: 20px;
    height: 20px;
    box-shadow:
      0 0 0 0,
      0 0 0 0,
      0 0 0 0,
      0 0 0 0,
      0 0 0 0,
      0 0 0 0,
      0px 0px 0 10px inset;
  }
  100% {
    transform: rotate(0deg);
    margin-top: -2px;
    margin-left: -2px;
    width: 20px;
    height: 20px;
    box-shadow:
      0 0 0 0,
      0 0 0 0,
      0 0 0 0,
      0 0 0 0,
      0 0 0 0,
      0 0 0 0,
      0px 0px 0 0px inset;
  }
}
@keyframes rippleOn {
  0% {
    opacity: 0;
  }
  50% {
    opacity: 0.2;
  }
  100% {
    opacity: 0;
  }
}
@keyframes rippleOff {
  0% {
    opacity: 0;
  }
  50% {
    opacity: 0.2;
  }
  100% {
    opacity: 0;
  }
}