Fix layout issues around images on the About page for narrow screens (#471)

[marceloams]

Closes #471. In narrow screens (mobile), the images are now displayed above the text for improved readability.

[wbazant]

Thanks for making the changes, the text is more readable now! Would you be up for trying flex layouts?

The pictures don't need to be up to 160px if they're not to the side of the text, this 2x2 grid could take the whole width.

I think this would look even better in a flex layout too: the staff member's picture to the right, their name and email to the left, centered vertically, and jointly taking the whole width.