No margin on news pages

[hugovk]

Describe the bug

On mobile (Android / Chrome), pages like https://beeware.org/contributing/guide/policies/ai-policy/ look good:

But pages like https://beeware.org/news/buzz/2026/2026q2-roadmap/ don't have enough margin and are harder to read:

How to reproduce the bug

1. Go to https://beeware.org/news/buzz/2026/2026q2-roadmap/ on mobile

[mhsmith]

A narrow browser window on desktop also reproduces this.