There comes a day when one is isolated or semi-isolated when one needs meaty reading and to do lots of thinking. I have so many bookmarks for such days! The one I was mulling just now is an academic one. Academic books cost an arm and a leg and then another arm, so this site is a gem: https://www.cambridge.org/core/what-we-publish/open-access
I want to collect a series sites like this and string them up so that I can chose, at will. That makes them a necklace rather than a single gem. Mostly I use them for research, but some days I browse and the browsing is lovely.