His comics were praised for being whimsical but also literary. It shifted between reality and a child's fantasy. He also added memorable and lovable characters that could be recognized due to his popularity (Calvin and Hobbes was featured in over 2,500 papers during its prime). He added satire and playful humor to many of his comics, which made them only that much more appealing.
He was also known for urging comic strip artists to print their comics outside of newspapers due to demands given by editors and syndicates.
The answer to this question is entasis.
Entasis is a design principle in architecture where in a convex curve was applied to a surface which also serves a strength to the construction and it also gives an optical illusion to it. Egyptian pyramids use this design principle.
