Simple dropdown menu without YUI

dropdown.css

.pure-menu-can-have-children:hover {
    background: #eee;
}

.pure-menu-can-have-children:hover ul {
  top: 35px; /* height of menu li */
  left: 0;
  visibility: visible;
  border: 1px solid #b7b7b7;
  background: #fff;
}

menu.html

<!-- includes pure-min.css -->
<div class="pure-menu pure-menu-open pure-menu-horizontal">
  <a href="/" class="pure-menu-heading">Heading</a>
  <ul class="pure-menu-children">
    <li class="pure-menu-can-have-children pure-menu-selected">
      <a href="/cars" class="pure-menu-label">Cars</a>
      <ul>
        <li>
          <a href="/cars?color=blue">Blue</a>
        </li>
        <li>
          <a href="/cars?color=red">Red</a>
        </li>
        <li>
          <a href="/cars?color=green">Green</a>
        </li>
      </ul>
    </li>
    <li>
      <a href="/trucks">Trucks</a>
    </li>
  </ul>
</div>