body:before {
  font-family: Helvetica, Arial, Sans-Serif;
  content: "oh no! build error!";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 100px;
  background-color: rgb(141, 55, 55);
  text-align: center;
  font-size: 2.5em;
  line-height: 2.5em;
  color: whitesmoke;
  text-shadow: -1px -1px rgba(0, 0, 0, 0.2)
}

body:after {
  font-family: Helvetica, Arial, Sans-Serif;
  content: '{REPLACE_ERRORS}';
  position: absolute;
  top: 100px; left: 0; right: 0;
  padding: 20px 50px;
  font-size: 1.25em;
  color: black;
  background-color: whitesmoke;
  border-bottom: 1px solid #aaa;
}