CSS vs. Crystal vs. Less vs. gitStream Comparison Chart

CSS, short for Cascading Style Sheets, is a style sheet language used by web developers to structure the HTML and other elements of a website. CSS is one of the most widely used languages on the web. For style sheets to work, it is important that your markup be free of errors. A convenient way to automatically fix markup errors is to use the HTML Tidy utility. This also tidies the markup making it easier to read and easier to edit. I recommend you regularly run Tidy over any markup you are editing. Tidy is very effective at cleaning up markup created by authoring tools with sloppy habits. Each style property starts with the property's name, then a colon and lastly the value for this property. When there is more than one style property in the list, you need to use a semicolon between each of them to delimit one property from the next.

Less (which stands for Leaner Style Sheets) is a backwards-compatible language extension for CSS. This is the official documentation for Less, the language and Less.js, the JavaScript tool that converts your Less styles to CSS styles. Because Less looks just like CSS, learning it is a breeze. Less only makes a few convenient additions to the CSS language, which is one of the reasons it can be learned so quickly. Mixins are a way of including ("mixing in") a bunch of properties from one rule-set into another rule-set. Less gives you the ability to use nesting instead of, or in combination with cascading.