rabbitholes: inline Wikipedia for any word on any page

Reading about the Thirty Years' War and hit 'Westphalian sovereignty' — a term I half-knew but couldn't actually define. New tab, read, come back, lost the thread. I built rabbitholes to fix that loop. Highlight any text and a shadow-DOM tooltip renders an explanation from Claude Haiku 4.5 next to your cursor. It doesn't rewrite the host page or inject visible DOM nodes — shadow DOM keeps the overlay isolated so no page's CSS bleeds into it or gets clobbered by it. The part I use most: click any