How can i add "focus" directly by the style tag in html?

Question

How can i add "focus" directly by the style tag in html? for ex: (I cant use stylesheet or javascript for this issue, since its inside mail) HTML Code:

<a href="#" style="a:focus { border: 1px solid #000; }">CLICK ME TO SEE THE BOUNDRIES</a>

Answer 1

According to this guide to CSS in emails, you have the ability to use <style> tags in the email, but this method is not supported at all by either GMail (both browser and mobile versions).

That being said, there is little to no support for the hover, visited, and focus selectors on any client.

I understand completely that cross-client incompatibility may not be a worthwhile compromise, but just know that this option is out there.