If anyone was wondering about the bd.style.css error, I’ve taken care of it by commenting out the following line in the theme’s functions.php
wp_enqueue_script( 'eaterstop_pro-testimonials-bootstrap', get_template_directory_uri().'/testimonialsrotator/js/bootstrap.js', array('jquery') );
So no more error appearing in the console 🙂
AFAIK, /testimonialsrotator/js/bootstrap.js not really contributing to the testimonial slider. There is also an error in that file (and some duplicate output code), but it’s not really worth discussing because the file isn’t needed.