.my-drop-zone {
  border: dotted 3px #d3d3d3;
}
.nv-file-over {
  border: dotted 3px #f00;
}
.another-file-over-class {
  border: dotted 3px #008000;
}
html,
body {
  height: 100%;
}
canvas {
  background-color: #f3f3f3;
  -webkit-box-shadow: 3px 3px 3px 0 #e3e3e3;
  -moz-box-shadow: 3px 3px 3px 0 #e3e3e3;
  box-shadow: 3px 3px 3px 0 #e3e3e3;
  border: 1px solid #c3c3c3;
  height: 100px;
  margin: 6px 0 0 6px;
}