Text jumps when switching between pages with and without demo

Mostly, this bug bugs me. :wink:

On a serious note: the page feels jumpy when you switch between components that have and don't have demos because the text shifts. It also does this when it first loads the demo:

The issue names no files or tests. Reproduce the jump by switching between components with and without demos, including the first demo load, and inspect the docs page layout involved. Done means the text remains stable during both transitions.

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