Bishwas-py In the meantime, you can use extend.php located in the root of your flarum install to do this. For example, I do this to point to an external CSS file (just easier for me to manage), but extend's capabilities can go much further than this.
use Flarum\Extend;
use Flarum\Frontend\Document;
use Flarum\Foundation\Event\Validating;
use Flarum\Discussion\DiscussionValidator;
use Illuminate\Contracts\Events\Dispatcher;
use Illuminate\Support\Str;
return [
(new Extend\Frontend('forum'))
->css('/var/www/vhosts/metabullet.com/httpdocs/forum.css')
->content(function (Document $document) {
$document->meta['theme-color'] = '#202020';
})
]