Preview:
javascript:(function(debug){var w=debug.documentElement.offsetWidth,t=debug.createTreeWalker(debug.body,NodeFilter.SHOW_ELEMENT),b;while(t.nextNode()){b=t.currentNode.getBoundingClientRect();if(b.right>w||b.left<0){t.currentNode.style.setProperty('outline','1px dotted red','important');console.log(t.currentNode);}};}(document));
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