.related-products {
  display: block;
}

.related-products__heading {
  margin: 0 0 4rem;
  text-align:center;
  font-size:39px;
  padding:0 0 1.5rem;
  position:relative;
}
.related-products__heading:after {
  content:"";
   position:absolute;
   height:1px;
   width:40%;
   background:black;
   bottom:0;
   left:50%;
   transform:translateX(-50%);
}