Hide scrollable content behind transparent fixed position divs when scrolling the page?

Question

I have a div called header that is set up with a fixed position. The problem is when I scroll the page the content of the page shows up behind the header (the header is transparent).

I know a lot about css, but cannot seem to figure this one out. I have tried setting overflow to hidden, but I knew it wouldn't work (and it didn't).

This is very hard to explain, so I did the best I could.

html:

<div id="header">
    <div id="topmenu">Home | Find Feeds | Subscriptions</div>
</div>
<div id="container">
    <div id="content">
        testing
    </div>
</div>

css:

#header {
    margin:0 auto;
    position: fixed;
    width:100%;
    z-index:1000;
}
#topmenu {
    background-color:#0000FF;
    height:24px;
    filter: alpha(opacity=50);
    opacity: 0.5;
}

#leftlinks {
    padding: 4px;
    padding-left: 10px;
    float: left;
}

#rightlinks {
    padding: 4px;
    padding-right: 10px;
    float: right;
}

#containerfixedtop {
    width: 100%;
    height: 20px;
}

#contentfixedtop {
    margin: 0 auto;
    background-color: #DAA520;
    width: 960px;
    height:20px;
}

#container {
    position: relative;
    top: 68px;
    width: 100%;
    height: 2000px;
    overflow: auto;
}

#content {
    margin: 0 auto;
    background-color: #DAA520;
    width: 960px;
    height: 2000px;
}

Here's a screenshot of the problem:

Answer 1

Just coming to this late, but in case anyone else runs across this in the future, here's your fix.

Your CSS Code:

.wrapper {
    width:100%;
    position:fixed;
    z-index:10;
    background:inherit;
}

.bottom-wrapper {
    width:100%;
    padding-top:92px;
    z-index:5;
    overflow:auto;
}

Your HTML:

<div class="wrapper">
    ...your header here...
</div>
<div class="bottom-wrapper">
    ...your main content here...
</div>

This will provide you with a header that cleanly matches your site, and floats at the top. The main content will scroll free of the header, and disappear when it passes the header. Your .bottom-wrapper padding-top should be the height of your header wrapper's content.

Cheers!