CSS for checkbox

checkbox.css

input[type='checkbox'] {
  opacity: 0;
}

input[type='checkbox'] + label {
  font: auto;
  position: absolute;
  // top: 25px;
  display: flex;
  align-items: center;
  transition: color 250ms cubic-bezier(.4,.0,.23,1);
  padding-top: 0.2em;
}

input[type='checkbox'] + label > span {
  font: 28px sans-serif;
  display: flex;
  justify-content: center;
  margin-right: 1em;
  width: 1em;
  height: 1em;
  background: white;
  border: 2px solid #9E9E9E; // border of box
  border-radius: 2px;
  cursor: pointer;
  transition: all 250ms cubic-bezier(.4,.0,.23,1);
}

input[type='checkbox'] + label:hover > span,
input[type='checkbox']:focus + label > span {
  background: white;
}

input[type='checkbox']:checked + label > ins {
  height: 100%;
}

input[type='checkbox']:checked + label > span {
  border: 0.5em solid #F1C232;
}

input[type='checkbox']:checked + label > span:before {
  content: "";
  position: absolute;
  top: 0.5em;
  left: 0.25em;
  border-right: 2px solid transparent;
  border-bottom: 2px solid transparent;
  transform: rotate(45deg);
  transform-origin: 0 100%;
  animation: checkbox-check 125ms 250ms cubic-bezier(.4,.0,.23,1) forwards;
}
@keyframes checkbox-check {
  0% {
    width: 0;
    height: 0;
    border-color: #212121;
    transform: translate3d(0,0,0) rotate(45deg);
  }

  33% {
    width: 0.2em;
    height: 0;
    transform: translate3d(0,0,0) rotate(45deg);
  }

  100% {
    width: 0.3em;
    height: 0.65em;
    border-color: #212121;
    transform: translate3d(0,-.5em,0) rotate(45deg);
  }
}