Talking about CSS

Basically, CSS is a language structure that describes the style of some HTML file (can also be used for XML), defining how it should be displayed. This structure allows developers to manage the behavior on one or multiple web pages; any change performed on some CSS element will be reflected in all HTML elements linked to it.

How does it work?

CSS is based on rules. These rules are defined on .css files, called style sheet. Style sheets can be composed of one or more rules, applied to one HTML or XML document; the rule has two parts: selector and declaration:

h4 { color : red}

The h4 element is the selector, and { color : red } is the declaration.

The selector works as a link between the document and the...