I have adjusted web-tiki's responsive square elements and I want to create a login screen.
On the login screen I want to use a header, and have the rest of the page fill the height and width of the screen precisely. It should look as follows filling the width and height:

Right now the code does not accomplishes this since the [FILL REST OF WIDTH AND HEIGHT WITH BACKGROUND IMAGE] part just resizes outside of my control.
HTML:
<div id="top">
    <h1>My header</h1>
</div>
<!-- Fixed main screen -->
<div id="login-screen" class="bg imgloginscreen">
    <div class="content rs">
        <div class="float-left">Some text, blabla</div>
        <div class="float-right">
            <form>
                <input type="text" value="Username"/><br/>
                <button type="submit">Login </button>
            </form>
        </div>
    </div>
</div>
CSS:
/* Responsive square elements stylesheet is adjusted from http://jsfiddle.net/webtiki/MpXYr/3/light/ which was designed by http://web-tiki.com/ */
#top {
    clear: both;
    margin: 0.25%;
    width: 99.5%%;
    padding: 0.1%;
    background-color: #000;
    color: #fff;
}
.imgloginscreen {
    background-image: url('http://upload.wikimedia.org/wikipedia/en/3/37/Leaves.JPG');
}
.content {
    position: absolute;
    height: 90%; /* = 100% - 2*5% padding */
    width: 90%; /* = 100% - 2*5% padding */
    padding: 5%;
}
/*  For responsive images */
.content .rs {
    width: auto;
    height: auto;
    max-height: 90%;
    max-width: 100%;
}
.float-left {
    float: left;
}
.float-right {
    float: right;
}
/* Not sure how to make it fill the rest of screen? */
#login-screen {
    float: left;
    position: relative;
    height: 99.5%;
    width: 99.5%;
    padding-bottom: 50%;
    margin: 0.25%;
    overflow: hidden;
    background-color: #1E1E1E;
}
body {
    font-family: 'Lato',verdana, sans-serif;
    font-size: 20px;
    color: #fff;
    text-align: center;
    background: #ECECEC;
    margin: 0;
}
I hope someone can help me make it fit in the screen.
Thanks.
JSFiddle: http://jsfiddle.net/2shygbcy/2/
 
     
     
    