Cascading Style Sheets is a technology that has been around for several years.
It's a great way to assign style properties to HTML elements in your web pages, and offers several significant benefits over the old way of putting style information directly into HTML tags.
Styles can be written in one place (separate style sheets) and assigned to HTML elements through class or ID properties. It's way easier and quicker to change styles across a whole site when they're defined in one place.
CSS is Lightweight
Using CSS (like class="main-nav") creates far smaller HTML files than writing style into every HTML tags (like border="1" cellpadding="3" cellspacing="1" backgroundcolor="#ffc").
CSS helps separate style from content
Keeping your style definitions separate from your content and content-structure makes it possible to re-purpose the same content for different media. This includes styling pages differently for printing, as well as other user agents like voice (text-to-speech) and mobile devices.
HTML elements can be displayed either in block or inline style. The difference between these is one of the most basic things you need to know in order to use CSS effectively.
(Not for beginners) Grids CSS is a suite of seven web page templates and the ability to nest grids of one to four columns within the content area of those templates. Together, the combined template and grid system enable you to implement over 100 different CSS layouts using only 1.82KB of includes.
