How to quickly copy block styles with inner elements?

Question

css

The task is this. Let's say I'm pulling a new template on the site. But there are blocks on the site for which the styles in the new template have not yet been made up.
And in order not to mess around for a long time, I want to transfer this entire block from the old template. How to quickly copy styles for a given block, including the styles of its nested elements. Maybe there is a browser extension?

Answer 1

ChromeDevTools, layout using BEM methodology and store blocks in separate files. Or use the gists from github.

Answer 2

We use sass (or less), we store block and element styles in separate files, we collect them using gulp