when looking for recommendations for software/web-apps that analyze/create/use CSS (cascading style sheets)
CSS (stands for Cascading Style Sheets) is a web language generally used in combination with HTML to edit the design of a site, by styling specific elements by their class/id/element type. CSS can seriously impact the look of the website; see W3Schools's example to see how big a difference it can make.
Use this tag in conjunction with a platform tag such as: web-apps, windows, osx, linux, etc... and only use it when you're seeking for something where CSS is a key element or requirement.
