text in .buttons iz center

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/web/branches/test@3024 92316355-f0b4-4df1-b90c-862c8a59935f

trac/htdocs/main.css

@@ -111,3 +111,7 @@ select, input[type="text"], input.textwidget, textarea {
 dt em { 
     color: #88AA77;
 }
+.buttons {
+    margin:0.5em 0;
+    text-align:center;
+}