Here's what I've got (keep in mind that I use the Dark Theme):

body
{
        margin: 0px;
        font-family: sans-serif;
}

pre, tt
{
        font-family: monospace;
}

a
{
        text-decoration: none;
}

a:hover
{
        background-color: cyan; color: #333;
}

pre > tt
{
        display: block;
        color: green;
        background-color: #333;
        border: solid #888 1px;
        padding: 10px;
        width: 90%;
        margin-right: 0px;
        margin-left: auto;
}

input[type=submit], input[type=text], input[type=checkbox], input[type
+=radio],
        select, textarea
{
        border: solid #333 1px;
}

input[type=submit], input[type=text]
{
        margin: 4px;
}
[download]

This way, my CSS won't make just any <pre> look like code, only <pre><tt>. I don't want to see every use of preformatted whitespace as code. Since I am selecting <tt> (an inline element) inside of <pre>, the styles apply to the <tt>; hence, the "display: block;" part.

This code still suffers from the problem of mis-styling a <tt> used inside <pre> in cases like: <pre>blah blah blah, <tt>Typewriter</tt> <strong>power</strong></pre> (I know, It's contrived). However, this is because CSS can't select (or disallow) so-called "anonymous" elements (i.e. text chunks).

Or, you can just do it your way, which is fine.

Update: since I was having problems with the Everything Engine messing with my square and pointy brackets, I moved my CSS into an external file. I have updated the code block to reflect my latest CSS.