`<pre>` / `<code>` formatting messes up ASCII boxes

[Saviq]

See https://mir-server.io/docs/how-to-use-checkbox-mir#heading--checkbox-mir--checkbox-cli

Something in how the code blocks are formatted breaks their monospace'ing.

The same block on Discourse is aligned: https://discourse.ubuntu.com/t/using-checkbox-mir-to-validate-your-snap-graphical-environment/37131#heading--checkbox-mir--checkbox-cli

[rsmelo92]

seems to be a problem with font family 'Ubuntu Mono variable'

https://github.com/canonical/mir-server.io/assets/16295402/83187c2c-7cc8-48f3-9963-e84d2699f97a

https://github.com/canonical/vanilla-framework/blob/c60ec0f7742b6ee8f564937142d4c9f3076a9360/scss/_settings_font.scss#L3

[carkod]

Yes this looks like something that should be filed on Vanilla