Minimal Responsive Dropdown Navigation In Pure CSS

A pure CSS multi-level dropdown navigation that will be converted into a mobile-friendly toggle menu in small screens.

How to use it:

Create a multi-level dropdown navigation from a nested nav list as this:

<nav>
  <ul>
    <li class="current"><a href="#">Home</a></li>
    <li><a href="#">About</a></li>
    <li><a href="#">Service</a></li>
    <li class="has_children"><a href="#">Contact</a>
      <ul>
        <li><a href="#">Facebook</a></li>
        <li><a href="#">Twitter</a></li>
        <li><a href="#">Email</a></li>
      </ul>
    </li>
    <li><a href="#">Portfolio</a></li>
  </ul>
</nav>

Create a menu toggle button using checkbox input and label.

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

The main CSS styles for the dropdown navigation on desktop.

nav ul ul { display: none; }
nav ul ul li { float: none; }
nav li { float: left; }
nav li a {
  text-decoration: none;
  display: inline-block;
  margin: 10px 20px 5px 0;
  padding: 8px 10px;
}
nav li a:link, nav li a:visited {
  color: #646565;
  background: #e8e9eb;
}
nav li a:link:hover, nav li a:visited:hover { color: black; }
nav li:hover ul {
  display: inline-block;
  position: absolute;
}
input.toggle, label.toggle { display: none; }
label.toggle {
  font-weight: 900;
  font-size: 1.2em;
  padding: 10px 20px;
}

Convert the dropdown navigation into to a toggle menu when the screen size is less than 960px.

@media (max-width: 960px) {
  nav { display: none; }
  input.toggle,  .toggle span { display: none; }
  input[type=checkbox]:checked ~ nav,  label.toggle {
    display: block;
    cursor: pointer;
  }
  nav li { float: none; }
  nav li:hover ul {
    display: block;
    position: relative;
  }
  nav li ul { display: block; }
  nav li ul li { margin-left: 20px; }
  nav li a {
    display: block;
    margin-left: 20px;
  }
}