[kiernan]

Is there a way to remove the styles but apply some others instead which highlight the borders and natural layout of the elements?

Kind of like if you turned off styles and used the inspect feature of your browser but with all it's mouse-over highlights and guidelines turned on at once.

[Hurtak]

You could combine the 'turn off css snippet' with something like this:

document.body.insertAdjacentHTML('afterbegin', '<style>{outline: 1px solid black}</style>')

both together:

javascript:[].slice.call(document.querySelectorAll('link,style,[style]')).forEach(function(e){e.style.cssText?e.style.cssText='':e.outerHTML=''});document.body.insertAdjacentHTML('afterbegin', '<style>{outline: 1px solid black}</style>');