Any way to display some heavily-styled HTML in isolation from the rest of site's styles?

Question

I am trying to figure out a way to display an archive of email newsletters on my client\'s site. The issue is that the newsletters are full of a zillion inline styles, whic

Answer 1

9 years later and there still isn't a better solution.

If you don't have an external source (you can't add html into a frame manually) you need to use js to insert the messy html/css (in my case I use it to view emails)

and js:

const frame = document.querySelector('.my-frame');

frame.contentWindow.document.open('text/html', 'replace');
frame.contentWindow.document.write(hereGoesYourMessyHtmlCss);
frame.contentWindow.document.close();