Fixed double-space typo.
diff --git a/user_guide/nav/hacks.txt b/user_guide/nav/hacks.txt
index 8c17f00..183481b 100644
--- a/user_guide/nav/hacks.txt
+++ b/user_guide/nav/hacks.txt
@@ -1,6 +1,6 @@
 I did the following hack in moo.fx.js:
 
-At line 79 in the toggle: function()  function, I added:
+At line 79 in the toggle: function() function, I added:
 
 document.getElementById('nav').style.display = 'block';