Unhighlighted code breaks the RTD theme

[ePirat]

When using the no-highlight class to prevent highlight.js to guess a specific highlighting, it works fine, but causes the Read the Docs theme to break, due to the absence of the hljs class I guess:

<pre>
    <code class="no-highlight">[…]</code>
</pre>

looks like this:

[ePirat]

This happens too when javascript is disabled.

[d0ugal]

Interesting, sounds like a CSS issue then.

[d0ugal]

Fixed by #416