Class Selector
CSS contextual selectors enable you to define style commands that can be utilized by many tags. When defining an contextual selector a period is placed before any selector name (Not to be confused with ID selectors that begin with #). When the contextual selector is used within a tag via class = the name of the selector variable only (no period preceding).

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CSS Tutorial For Beginners
In this tutorial, you will learn how to: Create an external CSS file and link it to multiple HTML files; Embed and import a style sheet; Create inline style sheets; Use tap selector and class selector; Set up font sizes, colors, faces and styles; Set up background color and image; Set up margins, text-align and decoration; Create layers; Set up atributes of the table, and more...

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Attributes as Selectors
The tutorial that will show you detail explanation of an attribute selector, what is it and how to use it.

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Advanced Selectors
Selectors are the way you reference the parts of your HTML documents with the styles you want to have applied to them. CSS2 and CSS3 brought with them a host of new selector specifications, designed to allow greater access to the elements and parts of those elements that make up each and every webpage.

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