Why does Prism syntax highlighter add a space in front of the CSS class?
<p>I'm using Prism syntax highlighter from <a href="http://prismjs.com" rel="nofollow noreferrer">http://prismjs.com</a></p>

<p>If I do something like</p>

<pre><code>&lt;!DOCTYPE html&gt;
&lt;html&gt;
    &lt;head&gt;
        &lt;link rel="stylesheet" type="text/css" href="prism.css"&gt;
        &lt;script type="text/javascript" src="prism.js"&gt;&lt;/script&gt;
    &lt;/head&gt;
    &lt;body&gt;
        &lt;pre&gt;
            &lt;code class="language-css"&gt;
p { color: blue }
            &lt;/code&gt;
        &lt;/pre&gt;
    &lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p>I see the following result in my Chrome Dev Tools:</p>

<pre><code>&lt;html&gt;
    &lt;head&gt;
        &lt;link rel="stylesheet" type="text/css" href="prism.css"&gt;
        &lt;script type="text/javascript" src="prism.js"&gt;&lt;/script&gt;
    &lt;/head&gt;
    &lt;body&gt;
        &lt;pre class=" language-css"&gt;
            &lt;code class=" language-css"&gt;
                &lt;span class="token selector"&gt;p&lt;/span&gt; &lt;span class="token punctuation"&gt;{&lt;/span&gt; &lt;span class="token property"&gt;color&lt;/span&gt;&lt;span class="token punctuation"&gt;:&lt;/span&gt; blue &lt;span class="token punctuation"&gt;}&lt;/span&gt;
            &lt;/code&gt;
        &lt;/pre&gt;
    &lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p>I know that Prism adds the <code>language-css</code> class to the <code>pre</code> tag. But where does the leading space (<code>" language-css"</code>) come from?</p>