I've looked into all of this and decided to do a CSS-only tooltip as best as is possible (to all the best standards, using hover etc.) + then add JS to do the things CSS can't (cancel the hover on mobile devices etc).
I definitely want to avoid jQuery (or any library) as many older mobiles struggle to run full jQuery code.
I've looked at the links above and also searched myself (although most need jQuery in my searches!).
Hopefully somebody can point me to a perfect tooltip that does these four things:
(2) completely responsive to screen size (and not having to set a width/height on the tooltip)
(3) allows for HTML content.
(4) a bonus would be a set of pre-styled options (of course I could style it myself but my CSS is average). I want to re-use this on a few sites.
Then I can take that, add the JS, and maybe post my completed version on here!
Thanks for the links Ralph and they all do some of these, but I can't find one that satisfies me yet.