Underline of text containing links in blogposts

Hi there, this CSS should do the trick:

.entry-content a,
.entry-content a:visited,
.entry-content a:hover {
    text-decoration: underline;
}

Error message:
(Using this plugin: https://wordpress.org/plugins/code-snippets/)

"Don't Panic

The code snippet you are trying to save produced a fatal error on line 1:
syntax error, unexpected '.', expecting end of file

The previous version of the snippet is unchanged, and the rest of this site should be functioning normally as before.

Please use the back button in your browser to return to the previous page and try to fix the code error. If you prefer, you can close this page and discard the changes you just made. No changes will be made to this site."

The code is CSS :) Here explains how to add, simplest way is Additional CSS in the Customiser

https://docs.generatepress.com/article/adding-css/