Cascading Style Sheets (css)

Cascading Style Sheets (CSS)

What is CSS?

CSS (cascading stylesheets) is a simple mechanism for

controlling the style of a Web document without compromising

its structure. By separating visual design elements (fonts,

colors, margins, and so on) from the structural logic of a Web

page, CSS give Web designers the control they crave without

sacrificing the integrity of the data - thus maintaining its

usability in multiple environments. In addition, defining

typographic design and page layout from within a single,

distinct block of code - without having to resort to image

maps, <font> tags, tables, and spacer GIFs - allows for faster

downloads, streamlined site maintenance, and instantaneous

global control of design attributes across multiple pages.

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How CSS Works

CSS overrides the browser's default settings for interpreting

how tags should be displayed, letting you use any HTML

element indicated by an opening and closing tag (including the

<p> tag) to apply style attributes defined either locally or in a

stylesheet.

Stylesheets contain rules, composed of selectors and

declarations that define how styles will be applied. The selector

(a redefined HTML element, class name, or ID name) is the link

between the HTML document and the style. There are two

different kinds of selectors: types (HTML element tags) and

attributes (such as class and ID names).

A CSS declaration has two parts,

a property ("color") and a value ("red").

The basic syntax of a rule

selector {property 1: value 1; property 2: value:

2}

An example (containing two declarations, as above)

P {font-size: 8pt; color: red}

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Local, Global, and Linked Stylesheets

Local (inline) stylesheet declarations, specific to a single

instance on a page, can be used instead of <font> tags to

specify font size, color, and typeface and to define margins,

leading, etc.

<p style="font size: small; color: red; font-weight:

bold; font-family: Ariel, Helvetica, non-serif">This

is a local stylesheet declaration. </p>

Global (embedded)