why my sub menu is not working in html css

Question

I have created my nav bar which was working fine but now i tried to add sub menu in my navbar and its not showing sub menu on hover. kindly check and correct me.

First I added <ul> in my <li> tag then I added css to hide nested <ul> then I tried to show <ul> on hover <li>

*{
  margin: 0;
  padding: 0;
}


nav{
  background-color: red;
}

ul{

  background-color: purple;
  width: 50%;	
}

nav ul li {
  list-style: none;
  padding: 5px;
  display: inline-block;   
}
nav ul li a{
  text-decoration: none;
  color:black;
font: bold 12px Arial;      
}

nav ul li:hover{
  background-color: blue;
  color: red;
}

nav ul li:hover a{

  color: red;
}

ul li ul {
  display: none;
  position:absolute;
}

nav ul li:hover ul {
    display:block;
}

<nav>
    <ul>
        <li> <a href="">Home</a></li>
        <li> <a href="">About Us</a></li>
        <li> <a href="">Contact Us</a></li>
        <li> <a href="">Privacy Policy</a></li>
        <li>
            <ul>
                <li><a href="">Submenu 1</a></li>
                <li><a href="">Submenu 2</a></li>
                <li><a href="">Submenu 3</a></li>
                <li><a href="">Submenu 4</a></li>
            </ul>
        </li>
    </ul>
</nav>

Answer 1

Looks like your <li> wrap is incorrect!

here is the fiddle

After Privacy Policy you have created another <li> that shouldn't be needed. you have to wrap the sub-menus with in privacy policy tag not a new one that is one of the reason why the css was not showing data as expected and you were almost there regarding CSS I just fixed it for you! hope it helps.

* {
  margin: 0;
  padding: 0;
}

nav {
  height: 30px;
}

nav ul {
  display: block;
  position: relative;
  z-index: 100;
}

nav ul li {
  float: left;
  list-style: none;
  margin: 0;
  padding: 0;
}

nav ul li ul {
  display: none;
}

nav ul li a {
  width: 100px;
  height: 30px;
  display: block;
  text-decoration: none;
  text-align: center;
  line-height: 30px;
  background-color: black;
  color: white;
}

nav ul li a:hover {
  background-color: red;
}

nav ul li:hover ul {
  position: absolute;
  top: 30px;
  display: block;
  width: 100px;
}

nav ul li:hover ul li {
  display: block;
}

<nav>
  <ul>
    <li> <a href="#">Home</a></li>
    <li> <a href="#">About Us</a></li>
    <li> <a href="#">Contact Us</a></li>
    <li> <a href="#">Privacy Policy</a>
      <ul>
        <li><a href="#">Submenu 1</a></li>
        <li><a href="#">Submenu 2</a></li>
        <li><a href="#">Submenu 3</a></li>
      </ul>
    </li>
  </ul>
</nav>

Answer 2

You have to add an anchor tag in the sub nav you have created. Because currently those sub-tabs are created but are not associated with any super-tab.

<a href="">Subnav</a>

So add this above your sub-nav code. You are good to go.

Answer 3

   *{
    margin: 0;
    padding: 0;
}


nav{
    background-color: red;
}

ul{

    background-color: purple;
    width: 50%; 
}

nav ul li {
    list-style: none;
    padding: 5px;
    display: inline-block;   
}
nav ul li a{
    text-decoration: none;
    color:black;
font: bold 12px Arial;      
}

nav ul li:hover{
    background-color: blue;
    color: red;
}

nav ul li:hover a{

    color: red;
}

ul li ul {
    display: none;
    position:absolute;
}

nav ul li:hover ul {
    display:block;
}

<nav>
<ul>
    <li> <a href="">Home</a></li>
    <li> <a href="">About Us</a></li>
    <li> <a href="">Contact Us</a></li>
    <li> <a href="">Privacy Policy</a></li>
    <li>
        <a href="">test</a>
        <ul>
            <li><a href="">Submenu 1</a></li>
            <li><a href="">Submenu 2</a></li>
            <li><a href="">Submenu 3</a></li>
            <li><a href="">Submenu 4</a></li>
        </ul>
     </li>
        

</ul>

Answer 4

Why don't you start from this working snippet and try to change data according to your needs :)

HTML Sub-Nav