导航栏元素堆叠在一起，我希望它们彼此相邻

<nav>
  <ul>
    <li><a href="#">导航项1</a></li>
    <li><a href="#">导航项2</a></li>
    <li><a href="#">导航项3</a></li>
  </ul>
</nav>

nav {
  position: relative;
}

nav ul {
  position: absolute;
  top: 0;
  left: 0;
  list-style: none;
  padding: 0;
  margin: 0;
}

nav ul li {
  display: inline-block;
  margin-right: 10px;
}

nav ul li a {
  display: block;
  padding: 5px 10px;
  background-color: #ccc;
  color: #fff;
  text-decoration: none;
}

nav ul li:nth-child(1) {
  z-index: 3;
}

nav ul li:nth-child(2) {
  z-index: 2;
}

nav ul li:nth-child(3) {
  z-index: 1;
}