checkbox.css

.card-duty input {
    position: absolute;
    opacity: 0;
    cursor: pointer;
    height: 0;
    width: 0;
  }
  
  /* Create a custom checkbox */
  .checkmark {
    position: absolute;
    top: 0;
    left: 0;
    height: 25px;
    width: 25px;
    background-color: #eee;
  }
  
  /* On mouse-over, add a grey background color */
  .card-duty:hover input ~ .checkmark {
    background-color: #ccc;
  }
  
  /* When the checkbox is checked, add a blue background */
  .card-duty input:checked ~ .checkmark {
    background-color: #2196F3;
  }
  
  /* Create the checkmark/indicator (hidden when not checked) */
  .checkmark:after {
    content: "";
    position: absolute;
    display: none;
  }
  
  /* Show the checkmark when checked */
  .card-duty input:checked ~ .checkmark:after {
    display: block;
  }
  
  /* Style the checkmark/indicator */
  .card-duty .checkmark:after {
    left: 9px;
    top: 5px;
    width: 5px;
    height: 10px;
    border: solid white;
    border-width: 0 3px 3px 0;
    -webkit-transform: rotate(45deg);
    -ms-transform: rotate(45deg);
    transform: rotate(45deg);
  }