Thank you!
It comes up so often and is something I'd been meaning to do for a while. I thought someone else might have already done it by now.
With the "blockquote" sections, are you suggesting that, for you, they are less noticeable? I agree with this and is the intention. I consider them "notes" and the entire tutorial should be able to be read without them; they are there for extra information. Maybe, "tip" might be appropriate if going along the alert route.
I actually intentionally avoided going into the baseline definition too much since it brings with it questions, namely "how do I find the baseline of my text?" and SFML doesn't actually give the ability to answer this question. The baseline in the example(s) is the bottom of bounds when the string is just "x", for example.
Sphinx is a good one indeed. Capitals, high lower-case letters, tittles, descenders etc..

I thought I had explained why there is an offset but it seems that I had not. Or, at least, not until you slowly get through the examples. So, I have added an extra note to explain the overall idea behind it (immediately after the sentence you mentioned).