Install Chameleon skin, at least version 4.3.0.
Clone this repo into skins/MardiSkin.
Add the following to LocalSettings.php:
wfLoadExtension( 'Bootstrap' );
wfLoadskin( 'chameleon' );
$wgDefaultSkin = 'chameleon';
$egChameleonLayoutFile= __DIR__ . '/skins/MardiSkin/layout.xml';
$egChameleonExternalStyleModules = [
__DIR__ . '/skins/MardiSkin/variables.scss' => 'beforeVariables',
__DIR__ . '/skins/MardiSkin/styles.scss' => 'afterMain',
];