[Solved] CSS for scrolling within masterpage

[topry]

Masterpage has a header, sidebar for navigation and the remainder contains a div that hosts the contentplaceholder. Usercontrols are loaded into the contentplaceholder when the user selects items in a list displayed on the left sidebar area.

    <div id="content" class="content" runat="server" >
        <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
        </asp:ContentPlaceHolder>
    </div><!-- end content -->

The style for this div is as follows:

.content {
    display:block;
    font-family: Arial, Helvetica, sans-serif;
    font-size: small;
    background-color: #FFFFFF;
    left: 218px;
    top: 85px;
    text-align: justify;
    position: fixed;
    margin: 85px,218px,0,0;
    overflow: auto;
    height: 100%;
}

The style for the header:

.header {
    display:block;
    top:0px;
    left:0;
    position:fixed;
    text-align:left;
    background:#00453D url(logo.gif) no-repeat fixed 0px 5px;
    height: 85px;
    vertical-align: bottom;
    padding: 0px;
    visibility: visible;
    border-bottom: 10px solid #FDDEA9;
    z-index: 1;
    width: 100%;
}

Everything works EXCEPT - the scrollbar for the div/contentplaceholder does not appear for the first 85px (the height of the header).
If I remove the .top value for .contentplaceholder, the scrollbar appears correctly, but of course the first 85px of the usercontrol loaded within the Contentplaceholder is clipped.

I've tried numerous different CSS settings w/out success (and a few of the above do not seem to have an impact).
If anyone has suggestions or even links to articles on CSS usage that might cover this, it would be appreciated.