I have my fonts sized larger than default and forced to Verdana so they stick out of some of the boxes.
It wouldn't be a ton of trouble to make the text bubbles expand to fit the text (one more div and splitting the background images, I suspect but won't confirm). But their goal was, I assume, to have a well-aligned, eye-catching 2x2 grid, and they chose not to support rare-ish cases where that wouldn't be what was rendered rather than cluttering their markup.