$(document).ready(f_init);

function f_init() {

    var oWB    = $("#whitebox"    );
    var oWBTop = $("#whiteboxtop" );
    var oWBBg  = $("#whiteboxbg"  );
    var oWBBot = $("#whiteboxbot" );
    var oWBCnt = $("#whiteboxcont");
    
    var nMin   = oWBTop.height()+oWBBot.height();
    if(oWBCnt.height()<nMin) {
        oWBCnt.height(nMin);
    }
    var nHeight = oWB.height()-oWBTop.height()-oWBBot.height();
    if(nHeight>0) {
        oWBBg.css({
            top   : oWBTop.height(),
            height: oWB.height()-oWBTop.height()-oWBBot.height()
        });
    }
    
}