Comment by coldsmoke

Addy Osmani has a "one-line debugger" that gives each element on the page a random colored outline.

    [].forEach.call(document.querySelectorAll("*"),function(a){a.style.outline="1px solid #"+(~~(Math.random()*(1<<24))).toString(16)})

https://gist.github.com/addyosmani/fd3999ea7fce242756b1