code: def normalize_rgb_colors_to_hex(css):
      
  
      regex = re.compile(r"rgb\s*\(\s*([0-9,\s]+)\s*\)")
      match = regex.search(css)
      while match:
          colors = [s.strip() for s in match.group(1).split(",")]
          hexcolor = '#%.2x%.2x%.2x' % tuple(map(int, colors))
          css = css.replace(match.group(), hexcolor)
          match = regex.search(css)
      return css
docs: Convert `rgb(51,102,153)` to `#336699`.