Modal window with top and bottom slices, but a variable height tiling center

by Admiral Potato

HTML

<!DOCTYPE html>
<html>
    <head>
        <title>CATS!</title>
    </head>
    <body>
        <div id="holder">
        <div class="modal_holder">
        <div class="modal_top"></div>
        <div class="modal_tile">
            <div class="modal_content">
                <h1>blah</h1>
                <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer egestas cursus fringilla. Aliquam varius arcu vel quam ultrices nec viverra quam pellentesque. Vivamus pretium, mi consequat sollicitudin vehicula, erat magna consequat libero, eget malesuada libero est interdum sem. Donec id velit nec odio tincidunt porttitor.</p>
                    <p>Aliquam varius risus risus. Vestibulum ultricies commodo dui, dictum eleifend turpis congue non. Praesent aliquet risus hendrerit risus vehicula mollis. Nunc est massa, lacinia a cursus gravida, ornare aliquam leo. Donec massa nisi, fermentum sit amet porta vel, varius ac lectus. Etiam in mauris tellus. Nulla in urna justo, ut accumsan risus. Aliquam at felis mauris, nec luctus diam. Quisque ac orci lorem.</p>
                <div class="end"><input type="button" value="lol"></div>
            </div>
        </div>
        <div class="modal_bottom"></div>
        </div>
        <br><br><br><br>
        <div class="modal_holder large">
        <div class="modal_top"></div>
        <div class="modal_tile">
            <div class="modal_content">
                <h1>WIDER!!!!</h1>
                <p>Donec ornare, nulla tristique aliquam semper, libero lacus fermentum libero, ut pellentesque lectus augue non nibh. Maecenas pretium feugiat leo vitae aliquet. Pellentesque et nisl sit amet augue lacinia rhoncus sed nec sapien.</p>
                <p>Nulla nec urna a nisl lacinia elementum. Aliquam erat volutpat. Sed elit lacus, sagittis ac bibendum eget, egestas at nisi. Aliquam sodales felis suscipit metus tristique ullamcorper rhoncus libero pulvinar.</p>
                    <p>Curabitur tempor orci ac augue imperdiet...

CSS

*{
    margin: 0;
    padding: 0;
    border: 0;
    outline: 0;
    vertical-align: inherit;
    font-size: inherit;
    line-height: inherit;
    font-weight: inherit;
    font-style: inherit;
    font-family: inherit;
    text-align: inherit;
    text-decoration: inherit;
    color: inherit;
    background-color: transparent;
}
*:focus{
    outline: none;
}
html, body{
    height: 100%;
    width: 100%;
}

body{
    background-color: #eee;
    background-repeat: no-repeat;
    background-position: top center;
    vertical-align: top;
    font-size: 14px;
    line-height: 24px;
    font-weight: 400;
    font-style: normal;
    font-family: helvetica, arial, sans-serif;
    text-align: left;
    text-decoration: none;
    color: #ccc;
}
h1{
    padding: 12px 0;
    font-size: 32px;
    line-height: 32px;
    color: #fff;
}
p{
    text-align: justify;
    padding: 4px 0;
}

#holder{
    padding: 128px 64px;
    z-index: 1;
}

.modal_holder{
    width: 608px;
    margin: 0 auto;
}
.modal_holder.large{
    width: 712px;
}

.modal_top,.modal_bottom{
    height: 96px;
    background-repeat: no-repeat;
}
.modal_top{
    background-image: url('http://beta.csc.com/images/new/modal_bg_top.png');
}
.large .modal_top{
    background-image: url('http://beta.csc.com/images/new/modal_bg_top_large.png');
}
.modal_bottom{
    background-image: url('http://beta.csc.com/images/new/modal_bg_bottom.png');
}
.large .modal_bottom{
    background-image: url('http://beta.csc.com/images/new/modal_bg_bottom_large.png');
}
.modal_tile{
    padding: 8px 0; /* Negative margins on children cannot escape parent unless parent has padding */
    background-image: url('http://beta.csc.com/images/new/modal_bg_tile.png');
    background-repeat: repeat-y;
    position: relative;
    z-index: 3;
    *zoom: 1;
}
.large .modal_tile{
    background-image: url('http://beta.csc.com/images/new/modal_bg_tile_large.png');
}
.modal_content{
    color: #333;
    margin: -104px 0; /* Extra 8px top and bottom...