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Form follows function — that has been misunderstood. Form and function should be one.
swap
A region whose content is replaced, like a page of a paginated list. The ink covers the old text, your code swaps the DOM underneath, and the new text is revealed; the height follows and focus lands on the new content.
With a view transition
The same swap run inside document.startViewTransition(): the browser morphs the region's box.
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Less, but better.