Workaround inconsistent text scaling (#100)

p + pre remains at em as we want to use the parent element here (however rem
could be used too, just requires a bigger value). I am setting it to 110% size,
otherwise some code blocks have relatively small text. The smaller code blocks
do appear bigger.

html.cfg

@@ -23,7 +23,7 @@ color: \#0060DF;
 }}
 
 \Css{p, a {
-font-size: 1.2em;
+font-size: 1.2rem;
 }}
 
 \Css{p + pre {