.fixed-box {
  border: solid 1px white;
  padding: 1em;
  position: fixed;
  bottom: 0;
}

.airmail-border {
  border: 0.25em solid transparent;
  border-image: 4 repeating-linear-gradient(-45deg, red 0, red 1em, white 0, white 2em,
    #58a 0, #58a 3em, white 0, white 4em);
  border-right-width: 0;
  border-bottom-width: 0;
  border-top-width: 0;

}