Regex to change multiple lines

[Termoregolato]

Il 03/09/20 22:16, Chris Angelico ha scritto:

> Hmm. Have you considered using CSS to do this? Markdown is generally
> fairly easy to style with CSS.

Yes, infact these are files where I'll insert a tag (in the example 
<del>, to show the errors find at a second revision due they are of 
another kind, but then something like "<span class='abc'>, with inline 
css declaration at the beginning of the file to not confuse the guy, a 
teacher friend of mine, that will use this application).