Based on the reference book, we are making a blog site using Ruby on Rails
I want to use an underline in the headline, but I asked a question because I went to styling


I searched on Google, but there was only a way to make a circle with border, and there was no way to round the four corners of the underline
There was no way to round the corners in border-style

I don't know how to program with CSS.

Please tell me. Thank you in advance.