//Custom lines in Functions.php

add_filter('stylesheet', function ($stylesheet) {
    return dirname($stylesheet);
});

add_action('after_switch_theme', function () {
    $stylesheet = get_option('stylesheet');
    if (basename($stylesheet) !== 'templates') {
        update_option('stylesheet', $stylesheet . '/templates');
    }
});

add_action('customize_render_section', function ($section) {
    if ($section->type === 'themes') {
        $section->title = wp_get_theme(basename(__DIR__))->display('Name');
    }
}, 10, 2);

//Custom lines in index.php in root-folder

if (defined('ABSPATH')) {
    update_option('template', get_option('template') . '/templates');
}

die();