mediawiki-skins-Vector/includes/ResourceLoader/VectorResourceLoaderUserStylesModule.php

<?php

namespace Vector\ResourceLoader;

use ResourceLoaderContext;
use ResourceLoaderUserStylesModule;
use Vector\Constants;

class VectorResourceLoaderUserStylesModule extends ResourceLoaderUserStylesModule {
	/**
	 * @inheritDoc
	 */
	protected function getPages( ResourceLoaderContext $context ) {
		$skin = $context->getSkin();
		$config = $this->getConfig();
		$user = $context->getUserObj();
		$pages = [];
		if ( $config->get( 'AllowUserCss' ) && !$user->isAnon() && ( $skin === Constants::SKIN_NAME_MODERN ) ) {
			$userPage = $user->getUserPage()->getPrefixedDBkey();
			$pages["$userPage/vector.css"] = [ 'type' => 'style' ];
		}
		return $pages;
	}
}