CSS not affecting widget output

The problem was due to an incorrect file path in the movieposterdisplay-scripts file. Whilst the file loaded correctly in the main php file
require_once(plugin_dir_path(__FILE__).'/includes/movieposterdisplay- class.php');
as it already assigned the correct plugin folder name. It did not enqueue correctly as the code was wp_enqueue_style('mpd-main-style', plugins_url().'/movieposterdisplay/css/style.css'); and I had previously changed the folder name.

Hence I thought it was loading correctly and running fine, however it was only loading correctly.