Remove last semi-colon within compressed CSS files generated by SASS, place this inside your config.rb.

config.rb

# Removes the last semi-colon in the CSS block
def cleansemi(filepath)
  # puts "cleaning: #{filepath}"
  text = File.read(filepath)
  replace = text.gsub(/;(.\s*)\}/m, '\1}')
  # puts replace
  File.open(filepath, "w") {|file| file.puts replace}
end

# Clean semi-colons with the stylesheet callbacks
on_stylesheet_saved do |filepath|
  # puts "about to clean: #{filepath}"
  cleansemi(filepath)
end