[css-pseudo] Fix markup.

Author: fantasai

css-pseudo/Overview.bs

@@ -256,7 +256,7 @@ The ::first-letter pseudo-element</h3>
   be a digit, e.g., the “6” in “67 million dollars is a lot of money.”
 
   If the characters that would form the ''::first-letter''
-  are not in the same element, such as "‘<code class="css">T" in <code>&lt;p&gt;'&lt;em&gt;T...</code>,
+  are not in the same element, such as <code>‘T</code> in <code>&lt;p&gt;‘&lt;em&gt;T...</code>,
   the user agent may create a ''::first-letter'' pseudo-element
   from one of the elements, both elements, or simply not create a pseudo-element.</code>
   Additionally, if the first letter(s) of the block