When I search for "contenteditable" in the React Docs Beta, zero results are shown:

The old website is much better:

Also, if you ask me, I find the React Docs Beta much less easier to read because:
- the search is worse
- there are no colored secions that ease reading the page (the whole page background is white)
- I can't expand sidebar menu sections wihtout causing the navigation
- the code blocks are barely distinguishable from the text now because you just made all UI elements have very similar white-ish color.
It is a degradation overall.