Disable or change readable line length in specific pages

[the_login]

For some notes, I need to disable readable line length because it’s messing with my content inside.

Things I have tried

I’ve found the following CSS snippet

body {
  --file-line-width: 1000px;
}

It works with the default theme (doesn’t work with Minimal theme), but I don’t understand how to enable it only on specific pages.

I know that it’s possible to use

---

cssclass: classname

In the page, but in this case, I don’t understand how to add a custom class

[the_login]

Solution, it’s just

.wide {
  --file-line-width: 1000px;
}

and then

---
cssclass:wide
---

that’s it