Render lists of type of and definitions differently

[annedino4]

See #92, point 7, When writing a function type expression (e.g. writing Bool -> Bool to indicate the type of function "not"), students try to click on types from the left-hand side list instead of the action panel. And because the "inspect type" page covers everything, it broke some students' mental flow (Let's discuss it in #103 )

After discussing with @dhess and Julia, I think the below design will prevent the students from thinking they can "use" them like using the action buttons:

The students will also be able to collapse both lists by selecting the chevron.

[annedino4]

Changed the heading fonts matching other parts of the UI to build better visual hierarchy.