body {
    background-color: burlywood;
    color: #3a3a3a;
}

h3 {
  border-bottom: solid 3px khaki;
  position: relative;
}

h3:after {
  position: absolute;
  content: " ";
  display: block;
  border-bottom: solid 3px lemonchiffon;
  bottom: -3px;
  width: 20%;
}