CSS Tucked Corner Effect

Helping out a Forrst user. Code by @jcfrog, I keep it here just because it's beautiful.

by AkaiKen

HTML

<!-- code by @jcfrog, I keep it here just because it's beautiful -->
<div class="tucked-corners top-corners">
    <span class="tucked-corners bottom-corners"> <!-- Span used for bottom corners -->
        <p>&amp;</p> <!-- Just for looks -->
    </span>
</div>

CSS

body {
    background: #e6e6e6...