Bootstrap 4自定义复选框未显示

<div class="custom-control custom-checkbox">
  <input type="checkbox" class="custom-control-input" id="customCheck1">
  <label class="custom-control-label" for="customCheck1">Check me</label>
</div>

.custom-checkbox .custom-control-input:checked ~ .custom-control-label::before {
  background-color: #007bff;
  border-color: #007bff;
}

.custom-checkbox .custom-control-label::before {
  content: '';
  position: absolute;
  top: 0.25rem;
  left: 0;
  display: block;
  width: 1rem;
  height: 1rem;
  pointer-events: none;
  border: #adb5bd solid 1px;
  background-color: #fff;
  border-radius: 0.25rem;
}

<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/js/bootstrap.min.js"></script>