All the changes can be found on your dev site in /bb-theme/less/theme.less. Therefore, it is as simple as coping the entire file contents and replacing the one you have you live site.
The changes to the menu module can be found on you dev site in /modules/menu/includes/frontend.css.php. Like above copy the entire contents of the file and replace what you have on your live site.
As this site is live, I would recommend performing a backup as a precaution.
We are having an issue with the menu module… On mobile, the menu toggles open when tapped but then immediately toggles closed. It won’t stay toggled open.