javascript - 让二级子菜单与主导航齐平

Question

现在，当您将鼠标悬停在 Offices > New York 上时，您会注意到嵌套的导航子菜单与“New York”选项齐平，上面有一些空白。

有没有一种 css 方法可以删除这个空白，以便嵌套的导航子菜单与顶部主导航齐平？ “信息”选项就在“芝加哥”旁边。显示信息、预订 session 、推荐的菜单。

或者javascript是否需要介入

.third-level-menu
{
    position: absolute;
    top: 0;
    right: -150px;
    width: 150px;
    list-style: none;
    padding: 0;
    margin: 0;
    display: none;
}

.third-level-menu > li
{
    height: 30px;
    background: #999999;
}
.third-level-menu > li:hover { background: #CCCCCC; }

.second-level-menu
{
    position: absolute;
    top: 30px;
    left: 0;
    width: 150px;
    list-style: none;
    padding: 0;
    margin: 0;
    display: none;
}

.second-level-menu > li
{
    position: relative;
    height: 30px;
    background: #999999;
}
.second-level-menu > li:hover { background: #CCCCCC; }

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

.top-level-menu > li
{
    position: relative;
    float: left;
    height: 30px;
    width: 150px;
    background: #999999;
}
.top-level-menu > li:hover { background: #CCCCCC; }

.top-level-menu li:hover > ul
{
    /* On hover, display the next level's menu */
    display: inline;
}


/* Menu Link Styles */

.top-level-menu a /* Apply to all links inside the multi-level menu */
{
    font: bold 14px Arial, Helvetica, sans-serif;
    color: #FFFFFF;
    text-decoration: none;
    padding: 0 0 0 10px;

    /* Make the link cover the entire list item-container */
    display: block;
    line-height: 30px;
}
.top-level-menu a:hover { color: #000000; }

<ul class="top-level-menu">
    <li><a href="#">About</a></li>
    <li><a href="#">Services</a></li>
    <li>
        <a href="#">Offices</a>
        <ul class="second-level-menu">
            <li><a href="#">Chicago</a></li>
            <li><a href="#">Los Angeles</a></li>
            <li>
                <a href="#">New York</a>
                <ul class="third-level-menu">
                    <li><a href="#">Information</a></li>
                    <li><a href="#">Book a Meeting</a></li>
                    <li><a href="#">Testimonials</a></li>
                    <li><a href="#">Jobs</a></li>
                </ul>
            </li>
            <li><a href="#">Seattle</a></li>
        </ul>
    </li>
    <li><a href="#">Contact</a></li>
</ul>

Answer 1

如果您从 .second-level-menu li 中删除 relative 位置，它将使第三级参照第一级。

.third-level-menu
{
    position: absolute;
    top: 0;
    right: -150px;
    width: 150px;
    list-style: none;
    padding: 0;
    margin: 0;
    display: none;
}

.third-level-menu > li
{
    height: 30px;
    background: #999999;
}
.third-level-menu > li:hover { background: #CCCCCC; }

.second-level-menu
{
    position: absolute;
    top: 30px;
    left: 0;
    width: 150px;
    list-style: none;
    padding: 0;
    margin: 0;
    display: none;
}

.second-level-menu > li
{
    height: 30px;
    background: #999999;
}
.second-level-menu > li:hover { background: #CCCCCC; }

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

.top-level-menu > li
{
    position: relative;
    float: left;
    height: 30px;
    width: 150px;
    background: #999999;
}
.top-level-menu > li:hover { background: #CCCCCC; }

.top-level-menu li:hover > ul
{
    /* On hover, display the next level's menu */
    display: inline;
}


/* Menu Link Styles */

.top-level-menu a /* Apply to all links inside the multi-level menu */
{
    font: bold 14px Arial, Helvetica, sans-serif;
    color: #FFFFFF;
    text-decoration: none;
    padding: 0 0 0 10px;

    /* Make the link cover the entire list item-container */
    display: block;
    line-height: 30px;
}
.top-level-menu a:hover { color: #000000; }

<ul class="top-level-menu">
    <li><a href="#">About</a></li>
    <li><a href="#">Services</a></li>
    <li>
        <a href="#">Offices</a>
        <ul class="second-level-menu">
            <li><a href="#">Chicago</a></li>
            <li><a href="#">Los Angeles</a></li>
            <li>
                <a href="#">New York</a>
                <ul class="third-level-menu">
                    <li><a href="#">Information</a></li>
                    <li><a href="#">Book a Meeting</a></li>
                    <li><a href="#">Testimonials</a></li>
                    <li><a href="#">Jobs</a></li>
                </ul>
            </li>
            <li><a href="#">Seattle</a></li>
        </ul>
    </li>
    <li><a href="#">Contact</a></li>
</ul>