CSS

CSS, Cascading Style Sheets, is a technology that complements HTML. Whereas HTML defines structure, CSS is focused on specifying the appearance of different HTML document elements. This specification can be embedded within an HTML document but is typically stored in a separate CSS file, supporting the design principle of ‘separation of concerns’.

As with our discussion of HTML, we will not go deeply into the details of how to use CSS, as that would require weeks of work; instead, we give you a grounding in the principles, along with pointers to where you can find out more.