A CSS "seam" (sunk-in line separator)

HTML

<div>
    <p> hello man! </p>
    <span class="seam"></span>
    <div>
        <p>Hello, this is some neat text</p>
        <p>This is another awesome paragraph</p>
        
    </div>
</div>

CSS

body {
    background: #aaa; /* a comment */
    /*another comment*/
}

.seam {
    clear: both;
    display: block;
    border-top: 1px solid rgba(0,0,0, .32);
    border-bottom: 1px solid rgba(255,255,255,.35);
}