Example given by Apeiros, how to use his css parser to edit CSS.

gistfile1.txt

css = Browsr::CSS.new
css.append_external_stylesheet(
  "#example-id { font-size: 12px; }", # the css definitions
  :author_style_sheet,                # origin of the definitions (relevant for specificity)
  Browsr::CSS::Media::AllMedia,       # media these rules apply for
  "(demofile)",                       # file  to report for definitions & errors
  1                                   # line to report for definitions & errors
)
ruleset = css.first # normally you'd ask for all rulesets for a given medium
rule    = ruleset.rules["#example-id"]
puts rule.to_css # prints the rule

rule['font-weight'] = "bold"
puts rule.to_css # prints the rule with the update applied