body {font-family:Arial,sans-serif;margin:20px;}
  .doc-row {display:flex;align-items:center;margin-bottom:8px;}
  .doc-row button {width:30px;height:30px;}
  .extra {margin-left:40px;margin-top:4px;}
  .extra-instance {margin-bottom:6px;}
  #preview {border:1px solid #ccc;padding:10px;margin-top:20px;white-space:pre-wrap;}
  .copy-btn {margin-top:10px;}

.switch {
  position: relative;
  display: inline-block;
  width: 60px;
  height: 34px;
}

.switch input {
  opacity: 0;
  width: 0;
  height: 0;
}

.slider {
  position: absolute;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  border-radius: 34px;
  background-color: #ccc;
  transition: .4s;
}

.slider:before {
  position: absolute;
  content: "";
  border-radius: 50%;
  height: 26px;
  width: 26px;
  left: 4px;
  bottom: 4px;
  background-color: white;
  transition: .4s;
}
input:checked + .slider {
  background-color: #2196F3;
}
input:checked + .slider:before {
  transform: translateX(26px); /* Shift the button when checked */
}