中心子菜单项具有可变宽度

Question

我试图将子菜单置于菜单项下面,但我似乎有一个障碍.这是我现在所处位置的一个工作示例:http://jsfiddle.net/zCWXb/

由于子菜单具有可变宽度,我似乎无法理解如何将其放置在相对于父菜单项的中心.

HTML:

<ul class="menu">
    <li><a href="#">Menu Item 1</a></li>
    <li><a href="#">Menu Item 2</a>
        <ul class="sub-menu">
            <li><a href="#">Sub Item 1</a></li>
            <li><a href="#">Sub Item Long Name Example 2</a></li>
            <li><a href="#">Sub Item 3</a></li>
        </ul>
    </li>
    <li><a href="#">Menu Item 3</a></li>
</ul>

CSS:

/*
    NAV
*/
body {
    background: #000;
}

.menu {
    position: absolute;
    left: 40px;
    top: 20px;
    color: #d6dcbd;
    font-family: 'nevis', Arial, "Arial Black", "Arial Bold", Gadget, sans-serif;
}
.menu .sub-menu {
    text-align: center;
    display:none;
    padding-top: 4px;
    width: auto;
    z-index: 20;
    position: absolute;
    left: -6px;
}
.menu .sub-menu li {
    text-align: center;
    background: #a9d6e4;
    display: block;
    float: none;
    width: auto;
    white-space: nowrap;
    padding: 4px 6px;
    margin-bottom: 3px;

    -webkit-border-radius: 3px;
    -moz-border-radius: 3px;
    border-radius: 3px;
}

.menu .sub-menu li a {
    color: #121212;
    text-transform: uppercase;
}
.menu .sub-menu li:hover {
    color: #FFF;
    background: #d6dcbd;
}
#menu-default > li {
    float: left;
    position: relative;
}

.menu li {
    width: auto;
    position: relative;
    display: block;
    float: left;
    padding: 0 25px 0 0;
}
.menu a {
    font-family: 'nevis', Arial, "Arial Black", "Arial Bold", Gadget, sans-serif;
    color: #d6dcbd;
    text-decoration: none;
}
.menu a:hover {
    color: #FFF;
}

.menu .current-menu-item a {
    color: #FFF;
}

jQuery的

$('.menu li').hover(
        //Mouseover, fadeIn the hidden hover class 
        function() {
            $(this).children('.sub-menu').stop(true, true).fadeIn('1000');   
        },
        //Mouseout, fadeOut the hover class
        function() {
            $(this).children('.sub-menu').stop(true, true).fadeOut('1000');  
    })

Answer 1

$('.menu li').hover(
        //Mouseover, fadeIn the hidden hover class 
        function() {
            var $this = $(this),
                $subMenu = $this.children('.sub-menu')
            $subMenu.stop(true, true).fadeIn('1000')
            .css("left", -1*($subMenu.width()/2) + $this.width()/2)         

        },
        //Mouseout, fadeOut the hover class
        function() {
            $(this).children('.sub-menu').stop(true, true).fadeOut('1000');  
})?;

工作演示 - http://jsfiddle.net/zCWXb/8/