body {
  background: #fff;
}

.dottedBorder {
  width: 600px;
  height: 150px;
  padding: 1em;
  border: 1px dashed transparent;
  background: linear-gradient(white, white) padding-box,
    repeating-linear-gradient(-45deg, #ccc 0, #ccc 0.25em, white 0, white 0.75em);
}