ul, li {
  margin: 0;
  padding: 0;
}

nav {
  grid-area: nav;
}

ul {
  list-style-type: none;
  cursor: pointer;
}

ul li:hover, ul li:active {
  color: #fff;
  background-color: #000;
}

#menu_header {
  display: none;
  color: #FF0000;
}

#menu_header:hover, #menu_header:active {
  color: #000;
  background-color: #fff;
  cursor: default;
}

#nav_section {
  display: flex;
  justify-content: space-between;
}

@media screen and (max-width: 650px) {
  nav {
    border-bottom: 1px solid #4B4B4B;
  }
  ul li {
    display: inline-flex;
    padding: 15px 25px;
  }
}

@media screen and (min-width: 650px) {
  nav {
    border-bottom: 1px solid #4B4B4B;
  }
  ul li {
    display: inline-flex;
    padding: 15px 25px;
  }
}

@media screen and (min-width: 900px) {
  nav {
    border-bottom: 0px;
    border-right: 1px solid #4B4B4B;
  }
  ul li {
    display: block;
    padding: 20px 0px 20px 0px;
  }
  #menu_header {
    display: block;
    padding: 20px 0px 15px 0px;
    margin: 0px;
  }
}