create a beautiful menu and li

nav {
  width: 100%;
  height: 50px;
  background-color: #333;
}
nav ul {
  margin: 0;
  padding: 0;
  list-style: none;
  position: relative;
}
nav ul li {
  display: inline-block;
  color: #fff;
}
nav ul li a {
  display: block;
  padding: 16px 20px;
  color: #fff;
  text-decoration: none;
}
nav ul li a:hover {
  background-color: #555;
}
nav ul li ul {
  display: none;
  position: absolute;
  top: 100%;
}
nav ul li:hover > ul {
  display: block;
  background-color: #fff;
  color: #555;
}
nav ul li ul li {
  display: block;
}