What does the term "typographical features" mean?

Technique of arranging type to make written language legible, readable, and appealing when displayed

B.F. Skinner

Skinner was the founder of behaviorism, positing that one could take a subject as a blank slate and use, consistently, both positive and negative reinforcement to push the subject toward certain behaviors and away from others. If the reinforcement or consequence was positive, the behavior would be more likely to be repeated. If it were negative, it would be less likely to be repeated.