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HTML

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CSS

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JavaScript

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Babel includes JSX processing.

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HTML 

              
                <body>

  <nav>
    <input type="checkbox" id="toggle" />
    <label for="toggle" class="hamburger">&#9776;</label>
    <!--     add a javascript function to hide the menu after being clicked -->
    <ul onclick="hidemenu()">
      <li><a href="#">Home</a></li>
      <li><a href="#">Information</a>
        <ul>
          <li><a href="#">Services</a></li>
          <li><a href="#">Support</a></li>
          <li><a href="#">Products</a></li>
        </ul>
      </li>
      <li><a href="#">About</a></li>
      <li><a href="#">News</a></li>
      <li><a href="#">Contact</a></li>
    </ul>
  </nav>

</body>
!

CSS 

              
                * {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: verdana, sans-serif;
  margin: 2em;
  padding: 0;
}

nav {
  width: 100%;
  position: fixed;
  top: 0;
  left: 0;
  background-color: silver;
}

nav ul {
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: flex-end;
}

nav ul li {
  flex: 0 0 8rem; /*the same as flex-grow, flex-shrink, flex-basis */
  text-align: center;
}

/* we turn off the underline and set the padding and the color O */

nav ul li a {
  text-decoration: none;
  padding: 0.8rem 1rem;
  display: block;
  color: green;
}

/* feedback for the user with a background when hovering hover */

nav ul li:hover {
  background-color: black;
}

nav ul li a:hover {
  color: white;
}

/* sub menus */

li ul {
  display: none;
  position: absolute;
  background-color: black;
}

li ul li a {
  padding: 0.3rem 1.5rem;
  /*   font-size: 0.8rem; */
}

nav ul li:hover ul {
  display: flex;
  flex-direction: column;
}

nav ul li ul li {
  flex: 0 1 auto;
  width: 8rem; /* the same as the value for flex-basis on the parent li */
}

/* now for the smaller displays */

@media screen and (max-width: 900px) {
  nav ul {
    flex-direction: column;
  }

  li ul {
    position: static;
  }

  nav ul li {
    flex: 0 0 auto; /*the same as flex-grow, flex-shrink, flex-basis */
    width: 100%;
  }

  nav ul li:hover ul {
    display: flex;
    flex-direction: column;
    width: 100%;
  }
}

/* Now let’s try with the hamburger menu

In this version we need to use a hamburger menu item that will reveal the menu. For this we need a checkbox as input that will toggle this on and off.

We need to add this the following HTML inside the nav */

/* <input type="checkbox" id="toggle">
<label for="toggle" class="hamburger">&#9776;</label> */

/* Note that ☰ is an HTML entity that displays the ☰ (hamburger icon.)

Now in the CSS we need to hide this item when we are in the normal wide screen view: */

/* we hide the hamburger icon until we are on a small screen */

input[type="checkbox"] {
  display: none;
}

.hamburger {
  display: none;
  font-size: 2rem;
  color: white;
  margin-right: 0.8em;
}

/* So when the display is small we can use our media query to hide the menu but reveal the hamburger */

@media screen and (max-width: 900px) {
  .hamburger {
    display: block;
    float: right;
    cursor: pointer;
  }

  /*   but we also need to hide the menu until that hamburger is clicked */

  nav ul {
    display: none;
  }

  /*when the hamburger is clicked the ul below it will be made to show */
  /*  the tilda ~ points to the next sibling selector */

  input[type="checkbox"]:checked ~ ul {
    display: block;
  }
}
!

JS 

              
                function hidemenu() {
  document.getElementById("toggle").checked = false;
}
!
999px

Console