GF home page: minor style changes

+ Split the list of languages into several columns if space permits
  (in supported browsers, currently Firefox).
+ Limit the size of the GF logo to 75% of width the window. Looks better on
  small screens.

index.html

@@ -255,7 +255,7 @@ syntax, lexicon, and inflection. The
 <A HREF="lib/doc/synopsis.html">GF resource grammar library</A> has
 support for an increasing number of languages, currently including
 </P>
-<OL>
+<ol class=languages>
 <LI>Afrikaans
 <LI>Amharic (partial)
 <LI>Arabic (partial)
@@ -291,7 +291,7 @@ support for an increasing number of languages, currently including
 <LI>Thai
 <LI>Turkish (fragments)
 <LI>Urdu
-</OL>
+</ol>
 
 <P>
 Adding a language to the resource library takes 3 to 9