@media screen and (min-width: 768px) {
  .nav li {
    width: 130px;
    border-bottom: none;
    height: 50px;
    line-height: 50px;
    font-size: 1.4em;
    display: inline-block;
    margin-right: -4px;
  }

  .nav a {
    border-bottom: none;
  }

  .nav > ul > li {
    text-align: center;
  }

  .nav > ul > li > a {
    padding-left: 0;
  }
  /* tu sub menu */
  .nav li ul {
    position: absolute;
    display: none;
    width: inherit;
  }

  .nav li:hover ul {
    display: block;
  }

  .nav li ul li {
    display: block;
  }
}