.my-drop-zone {
  -moz-border-bottom-colors: none;
  -moz-border-left-colors: none;
  -moz-border-right-colors: none;
  -moz-border-top-colors: none;
  border-bottom-color: lightgray;
  border-bottom-style: dotted;
  border-bottom-width: 3px;
  border-image-outset: 0 0 0 0;
  border-image-repeat: stretch stretch;
  border-image-slice: 100% 100% 100% 100%;
  border-image-source: none;
  border-image-width: 1 1 1 1;
  border-left-color: lightgray;
  border-left-style: dotted;
  border-left-width: 3px;
  border-right-color: lightgray;
  border-right-style: dotted;
  border-right-width: 3px;
  border-top-color: lightgray;
  border-top-style: dotted;
  border-top-width: 3px;
}

.nv-file-over {
  border: dotted 3px red;
}