.navbar-brand::after {
  content: "";
  position: absolute;
  background: url(../images/ch03b.png) 0 0 no-repeat;
  background-size: auto;
  background-size: contain;
  width: 52px;
  height: 44px;
  top: -11px;
  left: -10px;
}

@media (max-width: 768px) {
  .navbar-brand::after {
  width: 30px;
  top: -11px;
  left: -11px;
  top: -2px;
  left: -5px;
  }
}