I'm trying to use this technique to keep variables separated between different notebooks. It seems to be working fine, except that variables turn black as soon as they are evaluated — any ideas why this would be happening? Here are some examples:
And with a variable that hasn't been used at all:
Suddenly it's black, even though it has no value:
Options[$FrontEnd, AutoStyleOptions]
(also see in the options inspector) $\endgroup$