I'm not sure if this is possible with css, it could be.
I have solved similar issue with javascript:
window.top.innerHeight;
gets the available height, excluded menubars etc. of the borwser.
See how I did for the height, my issue was that the footer should be at the bottom even if content was empty-> 
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>C-Driver Manager</title>
<meta name="keywords" content="Aygit,Device,Driver,Surucu,Download,Indir,yedekle,Unknown,Bilinmeyen,Backup,Back-up,stuurprogramma,apparaat,windows,w7,w8,w10,multilanguage,tool,free,gratis,ucretsiz">
<meta name="description" content="Windows 7/8/10 Device indentify, Driver backup, Driver info">
<link rel="stylesheet" type="text/css" href="main.css">
<link rel="icon" href="images/favicon.ico">
</head>
<body onResize="resizecontainer();">
    <div class="divtop"> 
        <div class="divtopcontainer">
            <div class="divlogo">
            </div>
            <div class="divHmenu">
                <style>
    .mnuHorizontal
    {
        list-style:none;
    }
    .mnuHorizontal li
    {
        float:left;
    }
    .mnuHorizontal .activemnu a,.mnuHorizontal li a:hover
    {
        background:#00B7EF;
        border-radius:5px;
        color:white;
    }
    .mnuHorizontal li a
    {
         display:inline-block;
         text-decoration:none;
         padding:5px 12px;
         text-align:center;
         font-weight:bold;
         color:#020042;
    }
    </style>
<ul class="mnuHorizontal">
    <li id="index.php"><a href="index.php">HOME</a></li>
    <li id="features.php"><a href="features.php">FEATURES</a></li>
    <li id="download.php" class="activemnu"><a href="download.php">DOWNLOAD</a></li>
    <li id="contact.php"><a href="contact.php">CONTACT</a></li>
</ul>  
            </div>
        </div>
    </div>
    <div class="divblueline"></div>
    <div class="divcontainer">
<div style="float:left">
    <h2>What is C-Driver Manager</h2>
    C-Driver Manager is a simple tool that;
    <ul>
        <li>displays information about your devices</li>
        <li>identify unrecognized devices by windows</li>
        <li>Backups your devices driver</li>
    </ul>
<h2>Why C-Driver Manager?</h2>
<ul>
    <li>No installation needed</li>
    <li>No adware</li>
    <li>No spyware</li>
    <li>Absolutely freeware</li>
</ul>
</div>
<div>
    <img alt="" src="images/devmgr5.jpg" height="430" width="700">
</div>
</div>
    <div class="divblueline"></div>
    <div class="divbottom">
        <div id="chmx">
        </div>
    </div>
</body>
    <script>
        for (i=0;i<document.getElementsByClassName('mnuHorizontal').item(0).children.length; i++)
        {
            if (document.getElementsByClassName('mnuHorizontal').item(0).children[i].id ==
                "index.php")
            {
                document.getElementsByClassName('mnuHorizontal').item(0).children[i].className = 'activemnu';
            }
            else
            {
                document.getElementsByClassName('mnuHorizontal').item(0).children[i].className = '';
            }
        }
        resizecontainer();
        function resizecontainer()
        {
            avh     =   window.top.innerHeight;
            dbh     =   document.getElementsByClassName('divbottom').length *
                        document.getElementsByClassName('divbottom').item(0).clientHeight;
            dbt     =   document.getElementsByClassName('divtop').length    *
                        document.getElementsByClassName('divtop').item(0).clientHeight;
            dbbl    =   document.getElementsByClassName('divblueline').length   *
                        document.getElementsByClassName('divblueline').item(0).clientHeight;
            decrh = dbh + dbt + dbbl;
            document.getElementsByClassName('divcontainer').item(0).style.minHeight = (avh - decrh) + 'px';
        }
    </script>
</html>
look for this function inside the example above ->
function resizecontainer()
        {
            avh     =   window.top.innerHeight;
            dbh     =   document.getElementsByClassName('divbottom').length *
                        document.getElementsByClassName('divbottom').item(0).clientHeight;
            dbt     =   document.getElementsByClassName('divtop').length    *
                        document.getElementsByClassName('divtop').item(0).clientHeight;
            dbbl    =   document.getElementsByClassName('divblueline').length   *
                        document.getElementsByClassName('divblueline').item(0).clientHeight;
            decrh = dbh + dbt + dbbl;
            document.getElementsByClassName('divcontainer').item(0).style.minHeight = (avh - decrh) + 'px';
        }