I'd like to parce a CSS file and add before every CSS selector another selector. From: p{margin:0 0 10px;} .lead{margin-bottom:20px;font-size:21px;font-weight:200;line-height:30px;} I'd like: .mySelector p{margin:0 0 10px;} .mySelector .lead{margin-bottom:20px;font-size:21px;font-weight:200;line-height:30px;} But my CSS file is really complex (in fact it is the bootstrap css file) so the regex should match all CSS selectors. For now I have this regex: ([^\r\n,{};]+)(,|{) and you can see the result here http://regexr.com?328ps but as you can see there are a lot of matches that shouldn't match for example: text-shadow:0 -1px 0 rgba(0, matchs positive but it shouldn't Does someone have a solution ? THX