Don't shrink the size of the synopsis so much

[SVN r23652]

doc/html/boostbook.css

@@ -116,7 +116,6 @@ i.firstterm
       border:           0.2em ridge cyan;
       padding:          1pc;
       font-family:      Courier, Lucida Console;
-      font-size:        80%;
    }
 
    .boost-head