style(monarch.css): Add monospace default for code

Not every OS has `Consolas` as an installed font, for those browsers, default to `monospace`.

website/monarch/monarch.css

@@ -201,7 +201,7 @@ pre   { border: 1px solid #888
       }
 
 
-code, pre,dt { font-family: Consolas }
+code, pre,dt { font-family: Consolas, monospace }
 
 strong    { color: black }
 
@@ -216,4 +216,4 @@ dt    { color: navy; margin-top: 2ex; padding: 2px;}
 dl dl dt { margin-top: 1ex;}
 
 #documentation .keyword  { color: blue; }
-#documentation .tag      { color: navy; }
+#documentation .tag      { color: navy; }