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CSS

CSS. Cascading Style Sheets. Cascading Style Sheet (CSS). A cascading style sheet (CSS) is a set of rules that define styles to be applied to entire Web pages or individual Web page elements.

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CSS

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  1. CSS Cascading Style Sheets

  2. Cascading Style Sheet (CSS) • A cascading style sheet (CSS) is a set of rules that define styles to be applied to entire Web pages or individual Web page elements. • Each rule consists of a selector followed by a set of curly braces containing the style properties and their values. • The selector can be an HTML element, a user-defined style known as a class, or the ID of a specific element on a page.

  3. Sample CSS Style Rules a:link {color: rgb(255,204,0) } a:visited {color: rgb(153,204,204) } a:active {color: rgb(102,255,0) } h1, h2, h3{font-family: Verdana, Arial, Helvetica} h1 {color: rgb(255,204,0) } h2 {color: rgb(153,255,51) } h3 {color: rgb(0,255,204) } .callout { font-size: small } #trailer { font-family: serif }

  4. Three Kinds of Style Sheets • There are three ways of applying cascading style sheets to a Web page: external, embedded, and inline. • An external CSS keeps all the style definitions in a separate CSS file that you include in a Web page at runtime by using the <link> tag to apply the style sheet to the page. • An embedded CSS is a style sheet that gets copied physically into the head of the Web page and applies to theWeb page as a whole. • An inline CSS is a style sheet that applies to only one page element so it gets copied “inline” on the page with that element.

  5. Creating an Inline CSS • To create an inline CSS, you add a style parameter to the specific instance of the tag you want to style. • For example, consider the following inline styling of an h1 heading tag:<h1 style="background-color:#FFCC00">Welcome to My Home Page </h1> • When an inline CSS has more than one style change, you separate them with ;

  6. Creating an Embedded CSS • The embedded CSS goes in the head section between the <style> start and </style> stop tags: <head> <title>My Home Page</title> <style> h1 { font-family: Comic Sans MS; color: #0000DD } </style> </head>

  7. Creating an External CSS • When you want a style to apply to multiple Web pages, you create an external CSS and link the Web pages to it. • The Jade Valley site does this, for example, via the command:<link href="css/jadevalley.css“ rel="stylesheet" type="text/css" /> • Let’s create an external CSS to experience one in action.

  8. Creating a Style Class • In cascading style sheets, a class is a named definition of one or more styles. • You create the class by prefixing its name with a dot in the CSS file. For example:<style>.warning { color: red; font-family: arial; font-weight: bold}</style> • You use this class via the class parameter:<p>Be careful when you try this, because <span class="warning">the burner is hot!</span></p>

  9. CSS Page Layout • On the cutting edge of cascading style sheets is a feature called absolute positioning, which enables you to position page elements precisely onscreen based on x,y coordinates. • ITAW has a rock pile you can make. • Dreamweaver has absolute positioning layouts you can try.

  10. Eric Meyer • Eric Meyer is the Netscape standards evangelist who is generally credited with being the world’s expert on style sheets. • Meyer has recommended a cross-browser format for creating CSS layouts.

  11. Three-Column CSS Layout HTML{margin: 0; padding: 0} BODY{margin: 0; padding: 0} DIV.left{position: absolute; top: 3em; left: 0; width: 12.5%; padding:4px;font-size: 11px; background-color: white; border: 1px solid black; z-index: 10} DIV.middle{margin: 0 20% 1em 20%; padding: 0; background-color: pink} DIV.right{position: absolute; top: 4em; right: 0; width: 18%; font-size: 11px; z-index: 11}

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