On WikiMedia cluster, MediaWiki allows user to customize CSS and JavaScript.

On Agora, such customization is ignored, for example https://agora.nasqueron.org/User:Dereckson/timeless.css isn't loaded for the Timeless skin.

It appears it's actually an option, not enabled by default, on MediaWiki.

Querying current configuration:

$ mw shell agora
$wgAllowUserCss
= false

$wgAllowUserJs
= false

References:

• https://www.mediawiki.org/wiki/Manual:$wgAllowUserCss
• https://www.mediawiki.org/wiki/Manual:$wgAllowUserJs