其他Divs背后的超级下拉菜单

Question

我正在构建一个超级下拉菜单但是当我将鼠标悬停在其上时，其内容会出现在其他Div下面。

我搜索了一种方法来修复它，我读到了使用＆＃39; position：relative＆＃39;和＆＃39; z-index＆＃39;，但它不适用于我。

现在的样子：

我的HTML文件：

 <div id="nav">
    <ul id="menu">
        <li><a href="#" class="home">Home</a><!-- Begin Home Item -->
            <div class="dropdown_2columns"><!-- Begin 2 columns container -->
                <div class="col_2">
                    <h2>Welcome !</h2>
                </div>

                <div class="col_2">
                    <p>Hi and welcome here ! This is a showcase of the possibilities of this awesome Mega Drop Down Menu.</p>             
                    <p>This item comes with a large range of prepared typographic stylings such as headings, lists, etc.</p>             
                </div>

                <div class="col_2">
                    <h2>Cross Browser Support</h2>
                </div>

                <div class="col_1">
                    <img src="img/browsers.png" width="125" height="48" alt="" />
                </div>

                <div class="col_1">
                    <p>This mega menu has been tested in all major browsers.</p>
                </div>
            </div><!-- End 2 columns container -->   
        </li><!-- End Home Item -->
    </ul>
</div>

<div id="content">
    <h1> Content Test </h1>
</div>

CSS文件：

#content {
    margin:10px auto 0px 429px;
    position:relative;
    z-index: 1;
}


/* Navigation Bar */ 
#nav {
    width:100%;
    /* Background color and gradients */
    background: #c92424;
    background: -moz-linear-gradient(top, #dd4343, #9e1c1c);
    background: -webkit-gradient(linear, 0% 0%, 0% 100%, from(#dd4343), to(#9e1c1c));
    margin: 0 0 1em 0;
    position:relative;
    z-index: 999;

}

#menu {
    list-style:none;
    position:relative;
    width:882px;
    margin:30px auto 0px 429px;
    height:43px;
    padding:0px 20px 0px 20px;

    /* Background color and gradients */

    background: #c92424;
    background: -moz-linear-gradient(top, #dd4343, #9e1c1c);
    background: -webkit-gradient(linear, 0% 0%, 0% 100%, from(#dd4343), to(#9e1c1c));

}


#menu li {
    float:left;

    text-align:center;
    position:relative;
    padding: 4px 20px 4px 20px;
    margin-top:7px;
    border:none;
}

#menu li:hover {

    height:21px;

    margin-top:1px; 
    padding: 11px 20px 11px 20px;
    /* Background color and gradients */
    background: white;
    /* background: -moz-linear-gradient(top, #e56e6e, #e56e6e);
    background: -webkit-gradient(linear, 0% 0%, 0% 100%, from(#e56e6e), to(#e56e6e)); */


}

#menu li a {
    font-family:Arial, Verdana, sans-serif;
    font-weight: bold;
    font-size:14px; 

    line-height:21px;
    color: #EEEEEE;
    display:block;
    outline:0;
    text-decoration:none;
    text-shadow: 1px 1px 1px #000;
}

#menu li:hover a {
    color:#c92424;
    text-shadow: 1px 1px 1px #FFFFFF;

}


/* Drop Down */

.dropdown_2columns, 
.dropdown_4columns  {
    margin:10px auto;
    float:left; 
    position:absolute;
    left:-999em; /* Hides the drop down */
    text-align:left;
    padding:10px 5px 10px 5px;
    border:1px solid #c92424;
    border-top:none;

    /* Gradient background 
    background:#F4F4F4;
    background: -moz-linear-gradient(top, #EEEEEE, #BBBBBB);
    background: -webkit-gradient(linear, 0% 0%, 0% 100%, from(#EEEEEE), to(#BBBBBB));

    /* Rounded Corners */
    -moz-border-radius: 0px 5px 5px 5px;
    -webkit-border-radius: 0px 5px 5px 5px;
    border-radius: 0px 5px 5px 5px;
}

.dropdown_2columns {width: 280px;}
.dropdown_4columns {width: 560px;}


#menu li:hover .dropdown_2columns, 
#menu li:hover .dropdown_4columns{
    left:-1px;
    top:auto;
}

/* Columns */

.col_1,
.col_2,
.col_4{
    display:inline;
    float: left;
    position: relative;
    margin-left: 5px;
    margin-right: 5px;
}
.col_1 {width:130px;}
.col_2 {width:270px;}
.col_4 {width:550px;}

/* Drop Down Content Stylings */

#menu p, #menu h2, #menu h3, #menu ul li {
    font-family:Arial, Verdana, sans-serif;
    font-weight: bold;
    line-height:21px;
    font-size:12px;
    text-align:left;
    text-shadow: 1px 1px 1px #FFFFFF;
}
#menu h2 {
    font-size:21px;
    font-weight:400;
    letter-spacing:-1px;
    margin:7px 0 14px 0;
    padding-bottom:14px;
    border-bottom:1px solid #666666;
}
#menu h3 {
    font-size:14px;
    color:#c92424;
    margin:7px 0 14px 0;
    padding-bottom:7px;
    border-bottom:1px solid #888888;
}
#menu p {
    line-height:18px;
    margin:0 0 10px 0;
}

#menu li:hover div a {
    font-size:12px;
    color:black;
}
#menu li:hover div a:hover {
    color:#c92424;
}

#menu li ul {
    list-style:none;
    padding:0;
    margin:0 0 12px 0;
}
#menu li ul li {
    font-size:12px;
    line-height:24px;
    position:relative;
    text-shadow: 1px 1px 1px #ffffff;
    padding:0;
    margin:0;
    float:none;
    text-align:left;
    width:130px;
}
#menu li ul li:hover {
    background:none;
    border:none;
    padding:0;
    margin:0;   
}

Answer 1

您的菜单背景是透明的。加上这个：

.dropdown_2columns{ background: white; }