Formatting in Layouts / Differentiating Editable Content

Simple enough question, but have not found a solution.
Consider the following layout view of a row in a table :

I’m generally happy with what I’m able to do with this layout. However, without clicking around, there is no way for the user to know if a text field is from a lookup column (ie, cannot be edited) or is one that they can change.

So in this instance, the Task and Task Description come directly from the connected project task, but the notes are left for the booking (there can be more than one booking per task!)

However, there is no UI difference at all between these sections. This is less of a problem when first making a task (as the notes row will be blank) but when using the view to update things, it is clunky - and experience tells me anything clunky is going to cause problems down the track with users!

Has anyone got any suggestions as to what I might be able to do in order to visually differentiate between info which is editable and that which is not?

Many thanks