Diagnostic.css is a stylesheet which allows the user to test for common errors in a page's markup. Inspired by Eric Meyer's diagnostic CSS file, this one is intended to flesh out accessibility related issues on a page.
If you're working with a site you own, add this (temporarily, of course) to your site to display the errors.
If you're checking work you don't have access to, use this as a user style.
In the future, I hope to add some generated content to better inform where/ what the problems are.
This is an open repo. Contribute to it, add to the documentation, submit an issue, etc.