Export opitmised CSS from coverage reports
Chrome DevTools had a bug around version 48 where the CSS coverage tool actually collected coverage data across pages. It was incredibly useful as you could then go through a site and export that coverage data and parse out the unneeded styles and whilst not perfect for dynamic style rules added by scripts, or pseudo rules, it produced effective results. Unfortunately they fixed the 'bug'.
I have seen scripts that go someway to replicate this functionality using things like puppeteer. It would be a useful to have a similar feature, where options exist for ignoring any CSS media queries and pseudo rules, that can scan either a whole site or range of pages that can aggregate coverage data across pages and parse out the unnecessary styles