a1 {
  position: relative;
  padding: 0.25em 1em;
  border-top: solid 2px black;
  border-bottom: solid 2px black;
}
a1:before, a1:after {
  content: '';
  position: absolute;
  top: -7px;
  width: 2px;
  height: -webkit-calc(100% + 14px);
  height: calc(100% + 14px);
  background-color: black;
}
a1:before {
  left: 7px;
}
a1:after {
  right: 7px;
}