Flexbox to avoid one source of overflow

[tracielin]

Consider using Flexbox, which can adjust columns widths based on the relative amount (%) of content in each column. Trades off having uneven columns (downside) to possibly not having content overflow from a column when that column width becomes smaller than the intrinsic width of the content (benefit).

[tracielin]

Examples of my pages where overflow is currently a problem:

• Anomalous coronary artery origins page (when viewed from iPhone 11)