[potch]

(I work for Mozilla) It captures the page cropped to the bounding box of the element, so any background content would also be captured. The results would not contain transparency.

[greggman]

So in other words it doesn't work if the element has children that are transformed (tested that). Still useful though

[philh]

And if there are non-child elements positioned to overlap with this one, presumably they get captured too?

[tedmiston]

What happens if there are elements below the one you're screenshotting by z-index?

[dubcanada]

You would see the element under it assuming it's possible. What this does is finds the bounding box cords and takes a full page screenshot and crops it to that region.

[MattBearman]

Are there any plans to make this available through a Javascript API? With appropriate security warnings of course.