Create compact pre rule.

Author: RyanMcG

css/theme/night.css

@@ -35,10 +35,14 @@ body {
 
 .reveal pre {
   font-size: 1em;
-  line-height: 1.4em;
+  line-height: 1.3em;
   font-family: 'Inconsolata', monospace;
 }
 
+.reveal pre.compact {
+  font-size: .8em;
+}
+
 .reveal pre code {
   padding: 0 .4em;
   font-family: 'Inconsolata', monospace;