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CSS - cascading style sheets

CSS - cascading style sheets Cascading Style Sheets (CSS) is a simple mechanism for adding style (e.g., fonts, colors, spacing) to Web documents. CSS - cascading style sheets Cascading Style Sheets (CSS) is a simple mechanism for adding style (e.g., fonts, colors, spacing) to Web documents.

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CSS - cascading style sheets

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  1. CSS - cascading style sheets Cascading Style Sheets (CSS) is a simple mechanism for adding style (e.g., fonts, colors, spacing) to Web documents.

  2. CSS - cascading style sheets Cascading Style Sheets (CSS) is a simple mechanism for adding style (e.g., fonts, colors, spacing) to Web documents.

  3. Advantages of Style Sheets • Saves time • Easy to change • Keep consistency • Give you more control over layout • Use styles with JavaScript => DHTML • Make it easy to create a common format for all the Web pages

  4. Applying a single style sheet to multiple documents

  5. Basic Structure of a Style • Each definition contains: • A property • A colon • A value • A semicolon to separate two or more values • Can include one or more values • h1 {font-size:12pt;color:red}

  6. Style Precedence • External style sheet • Embedded styles • Inline styles

  7. Three Style Types • Inline styles • Add styles to each tag within the HTML file • Use it when you need to format just a single section in a web page • Example • <h1 style=“color:red; font-family: sans-sarif”>IU</h1>

  8. Three Style Types • Embedded or internal styles • A style is applied to the entire HTML file • Use it when you need to modify all instances of particular element (e.g., h1) in a web page • Example • <style> • h1 {color:red; font-family:sans-serif} • </style>

  9. Creating an Embedded Style <head> <title>Embedded Example</title> <style> (default is “text/css”) Style declarations </style> </head> • A style declaration: • Selector {attribute1:value1; attribute2:value2; …} • Selector = an element in a document (e.g., a header or paragraph)

  10. An Example of an embedded style (p. 353 Fig 7-2) <head> <title>Getting Started</title> <style type=“text/css”> h1 {font-family: sans-serif; color: organge} </style> </head>

  11. Three Style Types • External style sheets • An external style sheet is a text file containing the style definition (declaration) • Use it when you need to control the style for an entire web site • Example • .{color:red; font-family:sans-serif} • Save this in a new document using a .css extension

  12. Creating an External Style Sheet • Open a new blank document in Notepad • Type style declarations • h1 {color:red; font-family:sans-serif;} • Do not include <style> tags • Save the document as filename.css

  13. Linking to Style Sheets 1 • Open an HTML file • Between <head> and </head> add • <link href=URL rel=“relation_type” type=“link_type”> • URL is the file.css • Relation_type=“stylesheet” • Link_type=“text/css” • Save this file and the .css file in the same web server directory

  14. h1 {font-family: sans-serif; color: orange} b {color: blue} An example of an external style sheet with an original html file <head> <title>Getting Started</title> <link href=“scraps.css” rel=“stylesheet” type=“text/css” /> </head> Text file of css named “stylesheet” html file

  15. Style Sheet Strategies • Wherever possible, place your styles in external style sheets • Take advantage of the power of CSS to have control over an entire Web site • At the top level of your web site: define a default global.css style sheet • Refine styles at sublevels with a section.css style sheet • Try to avoid using styles in tags

  16. Using IDs and Classes • 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>

  17. Working With Ids • To create an ID for a specific tag, use the property: • <tag ID=id_name> • To apply a style to a specific ID, use: • #id_name {style attributes and values}

  18. 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>

  19. Applying a style to a class

  20. Working With Classes • To create a class, enter the following in the HTML tag: • <tag CLASS=class_name> • <h1 CLASS=FirstHeader>IU</h1> • class_name is a name to identify this class of tags • To apply a style to a class of tags, use: • tag.class_name {style attributes} or • .class_name {style attributes}

  21. Working With Classes and Ids • The difference between the Class property and the ID property is that the value of the ID property must be unique: • you can’t have more than one tag with the same ID value • You can apply the same Class value to multiple document tags

  22. Working With DIV • <DIV> tag is used for blocks of text, e.g., paragraphs, block quotes, headers, or lists • To create a container for block-level elements, use: • <DIV CLASS=class_name> • Block-level elements • </DIV> • Class_name is the name of the class • You can substitute the ID proper for the Class property (with ID, the syntax for CSS style, #id_name {style attributes and values}

  23. Working With <DIV> DIV.Slogan {font-weigh:bold} style Maxwell…: “We teach… <DIV CLASS=Slogan>Maxwell Scientific’s new Slogan is:<BR>”We teach science”</DIV> Resulting text HTML code

  24. Working With <span> • With the <span> tag, you can use inline elements, e.g., <B>, <I> • To create a container for inline elements, use: • <span CLASS=class_name> • inline elements • </span>

  25. CSS for Page Layout • CSS manipulates the size and location of block-level elements • Block-level elements in HTML: • Heading tags, e.g., <H1>, <H2> • <p> • <blockquote> and <address> tags • List tags, e.g., <ul>, <ol>, <dl> • <div> • <body> • <hr> • <img>

  26. CSS for Page Layout • Parts of the block-level elements: • Margin • Border • Padding

  27. padding border margin CSS for Page Layout (Carey, 7.49) I appreciate the prompt delivery of the pack of star disks.

  28. Controlling the Margins • To define the margins of an element, use: • margin:value • where value = a length value (“em” is often used), a percentage (a margin proportional to the element’s width, or auto

  29. Controlling the Margins • To set margins on a side, use: • margin-top • margin-right • margin-bottom • margin-left • E.g., LI {margin-left:2em; margin-right:2em; margin-top:1em; margin-bottom:1em}

  30. Setting the Padding Size • To define padding, use: • padding: value • where value = a length value or a percentage (a padding proportional to the element’s width)

  31. Setting the Padding Size • To set margins on a side, use: • padding-top • padding-right • padding-bottom • padding-left

  32. Formatting the Border • Border can be set in three ways: • border-width • border-style • border-color

  33. Formatting the Border • To set the border,use border:width_value style color • To set the border on the side, use border-top border-bottom border-left border-right

  34. Formatting Width & Height of Block-Level Boxes • To set the width of a block-level element, use: • width:value • height:value • where value can be a length value, a percentage, or auto • E.g., textarea {width:225px; height:100px}

  35. Using the Float Attribute • To float (wrap) a block-level element, use: • float:margin • Where margin = right, left, none • To prevent an element from wrapping, use: • Clear:margin • Where margin=right, left, both, none

  36. Using the Float Attribute float:right width:50px clear:right float:right width:50px

  37. Formatting Hypertext Links • To remove the style of underlining hypertext, use: A {text-decoration:none} • 4 types of hyperlinks can be modified: A:visited {styles for previously visited links} A:link {styles for links that have never visited} A:active {styles for links that are currently being clicked} A:hover {styles when the mouse cursor is hovering over the link}

  38. End.

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