Created attachment 632002 [details] demo showing jerky border transition Stanzas in this demo move smoothly when hovered upon in Chrome and Opera while the transition tends to be jerky on desktop Firefox. Shows an issue with the current CSS3 transitions implementation in Gecko.
Hmm. Which part is jerky? I can only reproduce the jerkiness if I put my mouse somewhere that's inside the stanza at the old location but not the new one. Are you seeing something different?
That and also when I leave the mouse at a position half way the position of the full transition
Sure. But that's expected behavior here, no? If the stanza moves so that it's no longer hovered then the style stops applying and the transition is reversed. What you see in Chrome and Opera is that they simply don't update hover styles correctly (in general; it's not a transition-specific issue) unless the mouse is moved, so you end up in a situation where the stanza is not hovered but still has the hover styles applying; as soon as you move the mouse by even a pixel the text moves back to its original position.
Maybe duplicate of bug 652767, or maybe duplicate of something just about :hover since this doesn't really require transitions.