find rem value and replace with modified version

rem_replace.rb

# Find and modify all rem values
# To use, call file and pass in CSS dir
# eg. ruby rem_replace.rb ~/my_css_files

dir = ARGV[0]

Dir.glob(dir + '/*.css') do |css_file|
  # do work on files ending in .css in the desired directory
  puts "working on: #{css_file}..."
  
  # read file
  markup = File.read(css_file)
  
  # Find rem values in file
  # Convert to float and multiply by 0.625
  # Return as float, or as int if divisibe by 1
  new_contents = markup.gsub(/(?!\s)(\d+\.?\d*)(?=rem)/) do |val|
    new_val = val.to_f * 0.625
    new_val % 1 == 0 ? new_val.to_i : new_val
  end
  
  # Write changes to the file
  File.open(css_file, "w") { |file| file.puts new_contents }
end