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Working with Cascading Style Sheets

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  1. Working with Cascading Style Sheets Tutorial 7 New Perspectives on HTML and XHTML, Comprehensive

  2. Using Inline StylesSession 7.1 • Inline styles are easy to use and interpret because they are applied directly to the elements they affect. <element style=“style1: value1; style2: value2; style3: value3;…”> <h1 style=“text-align: center; font-family: Arial, Helvetica, sans-serif”> New Perspectives on HTML and XHTML, Comprehensive

  3. Using Embedded Styles • You can embed style definitions in a document head using the following form: <style> style declarations </style> Where style declarations are the declarations of the different styles to be applied to the document. New Perspectives on HTML and XHTML, Comprehensive

  4. Using an External Style Sheet • Because an embedded style sheet only applies to the content of the file it is embedded in, you need to place style declarations in an external style sheet to apply to the rest of the Web site. • An external style sheet is a text file that contains style declarations. • It can be linked to any page in the site, allowing the same style declaration to be applied to the entire site New Perspectives on HTML and XHTML, Comprehensive

  5. Using an External Style Sheet • You can add style comments as you develop an external style sheet. • /* comment */ • Use the link element to link a Web page to an external style sheet. <link href=“name.css” rel=‘stylesheet” type = “text/css” /> New Perspectives on HTML and XHTML, Comprehensive

  6. Using an External Style Sheet • You can import the content of one style sheet into another. • Add the following to either an embedded or an external style sheet • @import(name.css); New Perspectives on HTML and XHTML, Comprehensive

  7. Understanding Cascading Order • You can link a single style sheet to multiple documents in your Web site by using the link element or the @import element. • You can also link a single document to several style sheets. New Perspectives on HTML and XHTML, Comprehensive

  8. Applying a single style sheet to multiple documents New Perspectives on HTML and XHTML, Comprehensive

  9. Applying multiple sheets to a single document New Perspectives on HTML and XHTML, Comprehensive

  10. Style Precedence • External style sheet • Embedded styles • Inline styles New Perspectives on HTML and XHTML, Comprehensive

  11. Style Precedence • If two styles have the same weight then the one declared last has precedence. <style type=“text/css”> H1 {color: orange; font-family: sans-serif”} H1{color: blue; font-family: serif} </style> New Perspectives on HTML and XHTML, Comprehensive

  12. Style Precedence • You can override the precedence rules by adding the !important property to a style declaration <style type=“text/css”> H1 {color: orange !important; font-family: sans-serif”} H1{color: blue; font-family: serif} </style> Gives the orange colour precedence New Perspectives on HTML and XHTML, Comprehensive

  13. Style Inheritance • If a style is not specified for an element, it inherits the style of its parent element. This is called style inheritance. • Causes style declarations to cascade down through a document’s hierarchy • To set every element on a page to blue • Body {color: blue} • Every element on the page inherits this style New Perspectives on HTML and XHTML, Comprehensive

  14. Style Inheritance • To override style inheritance you specify an alternate style for one of the descendent elements of the parent. • Body {color: blue} • P {color: red} • Changes every element on the page to blue except for paragraphs and every element within a paragraph • !important property also overrides style inheritance New Perspectives on HTML and XHTML, Comprehensive

  15. Working with Selectors • CSS allows you to work with a wide variety of selectors to match different combinations of elements. • h1, h2, h3 {font-family: sans-serif} • h1 {color: blue} • h2 {color: red} • h1 headings are blue sans-serif • h2 headings are red sans-serif. New Perspectives on HTML and XHTML, Comprehensive

  16. Working with Selectors • Set all bold text to blue • b {color: blue } • Use contextual selectors to apply a style based on the context in which an element is used. • Eg, to apply a style to text within a list • li b {color: blue} • li is the parent element, b is the descendant element New Perspectives on HTML and XHTML, Comprehensive

  17. Simple and contextual selectors New Perspectives on HTML and XHTML, Comprehensive

  18. Attribute Selectors • Create an attribute selector to select an element based on the element’s attributes. • a {color: blue} – all <a> tags • a[href] {color: blue} – only hrefs, not anchors • See figure 7-13 in your text for a list of attribute selectors New Perspectives on HTML and XHTML, Comprehensive

  19. Using IDs and ClassesSession 7.2 • Use an id to distinguish something, like a paragraph, from the others in a document. • For example, to identify a paragraph as “head”, use the code: <p id=“head”>… </p> New Perspectives on HTML and XHTML, Comprehensive

  20. Classes • HTML and XHTML require each id be unique– therefore an id value can only be used once in a document. • You can mark a group of elements with a common identifier using the class attribute. <element class=“class”> … </element> New Perspectives on HTML and XHTML, Comprehensive

  21. Applying a style to a class New Perspectives on HTML and XHTML, Comprehensive

  22. Applying a style to a class and element New Perspectives on HTML and XHTML, Comprehensive

  23. Sizing Elements and Floating an Element • You can define the width of columns in a columnar layout using: width: value • You can use CSS to set an element’s height using: height: value • You can float a paragraph using: float: position New Perspectives on HTML and XHTML, Comprehensive

  24. Working with the div Element • The div element is a generic block-level element. <div> content </div> New Perspectives on HTML and XHTML, Comprehensive

  25. Setting the Display Style Values of the display style New Perspectives on HTML and XHTML, Comprehensive

  26. Setting the Display Style Values of the display style New Perspectives on HTML and XHTML, Comprehensive

  27. Working with the Box Model • The box model is an element composed of four sections: • Margin • Border • Padding • content New Perspectives on HTML and XHTML, Comprehensive

  28. The Box Model New Perspectives on HTML and XHTML, Comprehensive

  29. Working with the Box Model • Styles to set padding are similar to styles to set margins: • padding-top: value • padding-right: value • padding-bottom: value • padding-left: value New Perspectives on HTML and XHTML, Comprehensive

  30. Border Styles New Perspectives on HTML and XHTML, Comprehensive

  31. Border Style Types New Perspectives on HTML and XHTML, Comprehensive

  32. Using Pseudo-Classes and Pseudo-Elements • A pseudo-class is a classification of an element based on its status, position, or current use in the document. New Perspectives on HTML and XHTML, Comprehensive

  33. Using Pseudo-Classes and Pseudo-Elements • Rollover effects can be created using pseudo-classes. • Pseudo-elements are elements based on information about an element’s content, use or position. New Perspectives on HTML and XHTML, Comprehensive

  34. Positioning Objects with CSSSession 7.3 • The different positioning styles in the original CSS1 specifications were known as CSS-Positioning or CSS-P. • To place an element at a specific position on a page use: position: type; top: value; right: value; bottom: value; left: value; New Perspectives on HTML and XHTML, Comprehensive

  35. Working with Overflow and Clipping • The overflow property syntax: overflow: type New Perspectives on HTML and XHTML, Comprehensive

  36. Stacking Elements • Specify stacking order with: z-index: value z-index: 1 z-index: 3 z-index: 2 New Perspectives on HTML and XHTML, Comprehensive

  37. Working with Different Media • Specify output styles for particular devices in the media attribute of the link and style elements New Perspectives on HTML and XHTML, Comprehensive

  38. The @media Rule • You can also specify the output media within a style sheet using: @media type {style declarations} Where mediais one of the supported media types and style declarations are the styles associated with that media type. New Perspectives on HTML and XHTML, Comprehensive

  39. Media Groups • CSS2 uses media groups to describe basic facets of different media– and to differentiate between different types of media based on the ways they render content. • Continuous or paged • Visual, aural, or tactile • Grid (for character grid devices) or bitmap • Interactive or static New Perspectives on HTML and XHTML, Comprehensive

  40. Media Groups New Perspectives on HTML and XHTML, Comprehensive

  41. Hiding Elements • Two different styles that allow you to hide elements: • Display style • Visibility style New Perspectives on HTML and XHTML, Comprehensive

  42. Comparing the visibility and display styles Visibility hidden Object is hidden but still is part of the page flow Display: none Object is hidden and is removed from the page flow New Perspectives on HTML and XHTML, Comprehensive

  43. Using Print Styles • You can specify the size of a page, margins, internal padding, etc. of the page box. • Review the Reference Window on page HTML 420 for working with print styles. New Perspectives on HTML and XHTML, Comprehensive