nav {
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100%;
    box-sizing: border-box;
    font-size:16px;
}

nav ul {
  position: relative;
  margin: 0;
  padding: 0;
  list-style: none;
}
nav ul::after {
  display: block;
  clear: both;
  content: '';
}
nav ul li {
  position: relative;
  float: left;
  border-left: 1px solid #fff;
  border-right: 1px solid #fff;

}
nav ul li:not(:first-child) {
  border-left: none;
}

nav ul ul li:not(:first-child) {
  border-left: 1px solid #fff;
}

nav ul li:hover {
  background-color: rgba(255,255,255,.3);
}
nav ul li a ,
nav li ul li a {
  display: inline-block;
  width:9.25em;
  color: #fff;
  text-align: center;
  text-decoration: none;
  white-space: nowrap;
}

nav ul li a {
  padding: 1em;
}

nav li ul li a {
  padding: .5em;
}

nav ul ul {
  position: absolute;
  top: 100%;
  left: -1px;
  background-color: #ffaaaa;
}
nav ul ul li {
  float: none;
  margin: 0;
  border: 1px solid #fff;
}
nav ul ul li:not(:first-child) {
  border-top: none;
}
nav ul ul ul {
  position: absolute;
  top: -1px;
  left: 100%;
}

nav ul ul {
  display: none;
}
nav ul li:hover > ul {
  display: block;
}