Have never used sass before.
On my production server having to switch chmod 644 public/* then run /etc/init.d/apache2 restart to restart the server.
Once server has rendered the css, I then have to come back and run chmod 755 public/* to actually load the css, js and images.
If 755 has higher creds, why does it fail?
actual error is:
Errno::EACCES (Permission denied - /srv/www/mysite.com/myapp/public/stylesheets/custom.css):
Use this Command :
chmod 766 -Rf public/. it might be work for you