The content for all textbooks (DC, AC, ...) is missing since yesterday. Tried to access from desktop and mobile. The sections are there but there's nothing inside. Thought it was a temporary glitch, but apparently it isn't.

 

It looks like the content is actually still there. If I do a search for, say, the resistor color code, I get result links that lead me to the material in the text.

So I'm guessing, for now, that it's a temporary issue. Maybe something got migrated and that affected how the Textbook indexing is done. Let's see if it gets fixed in the next few days. If not, I'll ping the commercial side of the house (who maintain that material).

 

Sorry about that, we had the fix up on Sunday....never push code on a Friday :\