- 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
As Cascading Style Sheets mature as a language of design and a tool of Web site and application management, a deep understanding of how the language really works is essential. However, most people have learned CSS the same way they’ve learned HTML,by viewing source, copying template codes, reading books and articles. While this “bootstrap” method of learning is often the best way to find great techniques, it may not be the best for knowing how to manage, debug, customize and even advance those techniques.
What our training hasn’t necessarily provided are the core concepts within CSS. This is why the Core CSS series may contain simple examples of things you already know. You’ll just get to know them better here! In this foundational reference card, you’ll find not only a bit of history and rationale for use, rule structure and syntax, but also a thorough resource as to the Cascade, inheritance and specificity,core principles of CSS that will expand and strengthen your professional ability to work with CSS.
CSS RATIONALE AND USE
The idea behind CSS is not a new one. We’ve seen the separation of presentation before in desktop publishing, where master style sheets can be created to control the layout, typefaces and colors used in a given design. Cascading Style Sheets were conceived to do exactly that: Remove the style from the document and place it separately from the code to be styled.
The benefits, when used carefully, can be outstanding. Some benefits of using style sheets include:
- Design flexibility
More image options
Better typographic control
Far more flexible layout options
Print design support
Handheld device design support
- Easier site maintenance
One style sheet, infinite pages
Design changes are very easy
Changes can be made quickly
Reduces time to launch
- Measurable returns
Faster loading documents
Far smaller documents
User experience improves
SEO (search engine optimization) improves
The first proposal for CSS was made by Håkon Wium Lie, now CTO of Opera Software. He worked with Bert Bos to co-author the first CSS specification, which believe it or not, became a recommendation in 1996! By 1998 CSS 2.0 brought us richer options, as we find later in advancing versions CSS 2.1 and CSS 3.0.
|CSS 1.0||First proposed 1994, First specification in 1996||Still flawed CSS 1 portions in all CSS browsers|
|CSS 2.0||1998||No full implementation|
|CSS 2.1||Not yet published as a complete specification||Some close to complete implementations|
|CSS 3.0 (Modular)||Certain modules are ahead of others in development||Some CSS 3.0 features are implemented in versions of WebKit, Mozilla and Opera browsers|