# [HELP] Automatic Height Contentbox [FAST HELP NEEDED]

Hello everyone,

I have a problem, i wanted a contentbox (sliced) that gets longer when the page in the frame is longer then the contentbox.
I hope someone gets that sentence, i created this code:

        <div id="middle">
        <div id="content_header"></div>
        <div class="content_box">
          <script type="text/javascript">

    //<![CDATA[
    window.onload = function() {
    var f = document.getElementById("mainframe");//Sets iframe id
    function resize() { //Starts resize function
    var h = "#";
    var w = "#";
    if (f.contentDocument) {
    h = f.contentDocument.documentElement.offsetHeight + 100 + "px";
    // can't find anything for Opera and Firefox that works for the width. OffetWidth doesn't work right either.(f.contentDocument.documentElement,"").getPropertyValue("width");
    } else if (f.contentWindow) {
    h = f.contentWindow.document.body.scrollHeight + 10 + "px";
    } else {
    return;
    }
    f.setAttribute("height",h);
    f.parentNode.setAttribute("height",h);
    }
    if (window.addEventListener) {
    f.onload = resize;
    } else if (f.attachEvent) {
    f.attachEvent("onload", resize);
    } else {
    return;
    }
    resize(); //starts resize function that was coded further up the code
    }
    //]]>
            </script>
          <iframe name="content_box" id="content_box" src="home.htm" width="100%" frameborder="0" allowtransparency="yes" scrolling="yes" border="0"></iframe>
          <br />
        </div>
        <div class="content_bottom"><br>
        </div>
        </div>

Code (markup):

Can someone please tell me what i'm doing wrong or what's wrong.
It's a really important code for my website. Thanks

Nathan