Hi Tuan,
I have a similar question—I'd like for links within my blog and portolio pages to be bold by default, but don't necessarily want links on the main pages to be bold. I copied both snippets you shared; the first snippet turned all links bold. The second snippet didn't make any links bold. Could you take a look at my site and see if you might be able to help me out? Really appreciate it.
https://www.wernetti.com/blog/kearsarge-pass-and-the-eastside