make navs turn to icons on small screens

conf.py

@@ -123,11 +123,16 @@ TRANSLATIONS_PATTERN = "{path}.{lang}.{ext}"
 
 NAVIGATION_LINKS = {
     DEFAULT_LANG: (
-        ("/install.html", "install"),
-        ("/doc", "documentation"),
-        ("/community.html", "community"),
-        ("/authors.html", "authors"),
-        ("/citing.html", "citing")
+        ("/install.html", "<i class='glyphicon glyphicon-download visible-xs-inline-block'></i>"
+        "<span class='hidden-xs'>install</span>"),
+        ("/doc", "<i class='glyphicon glyphicon-book visible-xs-inline-block'></i>"
+        "<span class='hidden-xs'>documentation</span>"),
+        ("/community.html", "<i class='glyphicon glyphicon-comment visible-xs-inline-block'></i>"
+        "<span class='hidden-xs'>community</span>"),
+        ("/authors.html", "<i class='glyphicon glyphicon-user visible-xs-inline-block'></i>"
+        "<span class='hidden-xs'>authors</span>"),
+        ("/citing.html", "<i class='glyphicon glyphicon-edit visible-xs-inline-block'></i>"
+        "<span class='hidden-xs'>citing</span>")
     ),
 }