Load slideshow.css file only if Slideshow is checked / on

Add a function to your functions.php file like this:

function slider_scripts() {
    wp_enqueue_style( 'slider-java-script', get_template_directory_uri() . '/css/slider-java-script.css' ); //change the location to work for you
}

Then add slider_scripts() to the top of the template part ( partials/slider/slider-java-script.php )