Earlier today, I wrote a translation note for post #3408511. As far as I can tell I didn't do anything unusual to write this note and I do not run any scripts for this sort of thing, but the text content of the note appears in the main note box, which is more opaque than usual.
I've seen this before on posts like post #3345089, so I'm sure there's also an intentional way of doing this, but it's never happened to me before. I have also added notes to other posts since the note in question, but they do not display the same behavior despite being done on the same computer, account, and browser.
Part of the reason I'm bringing this up is because of its properties. If I use either the html property "white-space:nowrap" or non-wrapping characters in the note's text, it can change the size of the note's main box. For a demonstration of this, I have intentionally misspelled "white-space:nowrap" in the note on the post in question. You'll see what I mean if you go into the note editor, fix the spelling, and hit "preview". Also, changing the spelling back to the incorrect version (which returns it to its current size) yields an error message reading "Error: Note must be inside the image". Does anyone know what's causing this?