CSS

What is CSS?

• CSS stands for Cascading Style Sheets
• Styles define how to display HTML elements
• Styles were added to HTML 4.0 to solve a problem
• External Style Sheets can save a lot of work
• External Style Sheets are stored in CSS files

Styles Solved a Big Problem

HTML was never intended to contain tags for formatting a document.

HTML was intended to define the content of a document, like:

<h1>This is a heading</h1>

<p>This is a paragraph.</p>

When tags like <font>, and color attributes were added to the HTML 3.2 specification, it started a nightmare for web developers. Development of large web sites, where fonts and color information were added to every single page, became a long and expensive process.

To solve this problem, the World Wide Web Consortium (W3C) created CSS.

In HTML 4.0, all formatting could be removed from the HTML document, and stored in a separate CSS file.

All browsers support CSS today.

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CSS Saves a Lot of Work!

CSS defines HOW HTML elements are to be displayed.

Styles are normally saved in external .css files. External style sheets enable you to change the appearance and layout of all the pages in a Web site, just by editing one single file!

CSS Syntax

A CSS rule has two main parts: a selector, and one or more declarations:

The selector is normally the HTML element you want to style.

Each declaration consists of a property and a value.

The property is the style attribute you want to change. Each property has a value.

HTML5

HTML5 is the next generation of HTML.

What is HTML5?

HTML5 will be the new standard for HTML, XHTML, and the HTML DOM.

The previous version of HTML came in 1999. The web has changed a lot since then.

HTML5 is still a work in progress. However, most modern browsers have some HTML5 support.

How Did HTML5 Get Started?

HTML5 is a cooperation between the World Wide Web Consortium (W3C) and the Web Hypertext Application Technology Working Group (WHATWG).

WHATWG was working with web forms and applications, and W3C was working with XHTML 2.0. In 2006, they decided to cooperate and create a new version of HTML.

Some rules for HTML5 were established:

• New features should be based on HTML, CSS, DOM, and JavaScript
• Reduce the need for external plugins (like Flash)
• Better error handling
• More markup to replace scripting
• HTML5 should be device independent
• The development process should be visible to the public

New Features

Some of the most interesting new features in HTML5:

• The canvas element for drawing
• The video and audio elements for media playback
• Better support for local offline storage
• New content specific elements, like article, footer, header, nav, section
• New form controls, like calendar, date, time, email, url, search

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Browser Support

HTML5 is not yet an official standard, and no browsers have full HTML5 support.

But all major browsers (Safari, Chrome, Firefox, Opera, Internet Explorer) continue to add new HTML5 features to their latest versions.