Learned D3 at Businessweek, started using Observable to do my job at Kensho, took time off to write notebooks about Mayans and Galton, moved to San Francisco to work for Observable. Now work for it remotely from the Berkshires where my wife runs Avaloch.
In the new version I no longer can expand and see the code, if it is not my notebook. Is this on purpose? Do I have to fork it first? That would be unfortunate.
On any notebook, you can click the pencil button in the bottom-left corner to enter tinker mode which allows you to see (and edit) the code without leaving the page.