CSS で真に水平なリストを作成するには?

ul#menuItems li {
  display: inline;
  list-style: none;
  margin-left: auto;
  margin-right: auto;
  top: 0px;
  height: 50px;
}

ul > li {
    display: inline-block;
}

ul#menuItems {
  background: none;
  height: 50px;
  width: 100px;
  margin: 0;
  padding: 0;
}
ul#menuItems li {
  display: inline-block;
  margin: 0;
  top: 0px;
  height: 50px;
}
ul#menuItems li a {
  font-family: Arial, Helvetica, sans-serif;
  text-decoration: none;
  font-weight: bolder;
  color: #000;
  height: 50px;
  width: auto;
  display: block;
  text-align: center;
  line-height: 50px;
}

<ul>