nav .gnb a:nth-child(2) {
  background-color: #f39220;
  color: white;
}
body {
  height: calc(100vh - 80px - 50px);
}

@media (max-width: 767px) {
  body {
    margin-top: 50px;
    height: calc(100vh - 50px - 30px);
  }
}