Web designers - Take note of the NYTimes.com header that appears after you scroll down to the content. These dynamically-appearing headers are a good idea, but nobody seems to get the nuance right.

If I scroll until the top of the article is at the top of the page, then start reading, I suddenly can't because this inept header just appeared covering the top 10% of the page. Now I have to scroll back up to see the content.

If it had appeared when the massive full-screen image WAS the top 10% it'd've been a perfectly seamless header introduction, but instead they wait until there's something valuable at the top of the page to introduce it.

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