Reformat and reformulate 2x2 buttons
- Reformat buttons such that they don't wobble so much between 1/2/3 line formats (by introducing larger max-width and minimum height)
- Reformulate buttons to same names as in Hamburger menu, where applicable
- Exchange links for education hamburger menu <> buttons, as of comment in #274
- Since principally all links of these 2x2 buttons are external, don't add explicit "external" symbol there. Is that appropriate?