simplify .example rule selector

Author: fantasai

default.css

@@ -143,9 +143,8 @@ pre.example:before {
     border: thin solid #999;
     /*margin: -1.3em 0 0.3em -2.5em;*/
 }
-div.example, div.illegal-example, div.html, div.illegal-html, div.xml,
-div.illegal-xml, pre.example, pre.illegal-example, pre.html,
-pre.illegal-html, pre.xml, pre.illegal-xml {
+.example, .illegal-example, .html, .illegal-html, .xml,
+.illegal-xml {
     background: #FFF8DD;
     padding: 0.5em;
     margin: 1em 0;