css+jquery 炫酷二级菜单

<ul class="menu">
  <li><a href="#">菜单1</a>
    <ul class="submenu">
      <li><a href="#">子菜单1-1</a></li>
      <li><a href="#">子菜单1-2</a></li>
    </ul>
  </li>
  <li><a href="#">菜单2</a>
    <ul class="submenu">
      <li><a href="#">子菜单2-1</a></li>
      <li><a href="#">子菜单2-2</a></li>
    </ul>
  </li>
</ul>

.menu {
  list-style: none;
  padding: 0;
}

.menu > li {
  display: inline-block;
  position: relative;
}

.submenu {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  background-color: #fff;
  border: 1px solid #ccc;
  box-shadow: 0 2px 5px rgba(0,0,0,0.2);
}

.submenu li {
  width: 100%;
}

.submenu li a {
  display: block;
  padding: 10px;
  text-decoration: none;
  color: #333;
}

$(document).ready(function() {
  $('.menu > li').hover(
    function() {
      $(this).find('.submenu').slideDown(200); // 滑动展开子菜单
    },
    function() {
      $(this).find('.submenu').slideUp(200); // 滑动收起子菜单
    }
  );
});