Look at how tiny JW is. Jodi is bigger. She's between 5'4-5'6, about the same height as JM.
The lower chair is to make her appear small, childlike (hmm, like they want to claim Travis told her to act?),one who couldn't defend herself, but by force, she had no choice. They are manipulating the jury. Dress them like schoolmarms and Sunday school teachers. Wearing glasses also are used as a tool.
It's a common trick. Look at Casey and her chair. You thought that one day all you would see was just the top of her head, her eyes looking over the table.