HyperText Markup Language- HTML HyperText Markup Language-
Learning outcomes Code web pages using HTML Explain why it is advisable to use XHTML rather than HTML Describe some technologies available for dynamic web pages Explore some problems of html
Essential Reading William Buchanan, Mastering The Internet, Ch. 6-8 Mike Lewis, “Understanding Javascript”, June-Jully 2000 Chuck Masciano and Bill Kennedy, HTML and XHTML the definitive guide, for reference http://www.pcnetworkadvisor.com Introductory materials on HTML & XHTML either a text book such as John Shelly, HTML AND CSS explained, or http:/www.webMonkey.com http://www.w3schools.com
What is an HTML File? HTML stands for HyperText Markup Language An HTML file is a text file containing small markup tags The markup tags tell the Web browser how to display the page An HTML file must have an htm or html file extension An HTML file can be created using a simple text editor
HTML contd. HyperText Markup Language--HTML is a collection of platform-independent styles (indicated by markup tags) that define the various components of a World Wide Web document. HTML was invented by Tim Berners-Lee while at CERN, the European Laboratory for Particle Physics in Geneva.
HTML Basics HTML documents are plain-text (also known as ASCII) files that can be created using any text editor (e.g., Emacs or vi on UNIX machines; SimpleText on a Macintosh; Notepad on a Windows machine). You can also use word-processing software if you remember to save your document as "text only with line breaks".
HTML Basics An element is a fundamental component of the structure of a text document. Some examples of elements are heads, tables, paragraphs, and lists. Think of it this way: you use HTML tags to mark the elements of a file for your browser. Elements can contain plain text, other elements, or both.
HTML Basics To denote the various elements in an HTML document, you use tags. HTML tags consist of a left angle bracket (<), a tag name, and a right angle bracket (>). Tags are usually paired (e.g., <H1> and </H1>) to start and end the tag instruction. The end tag looks just like the start tag except a slash (/) precedes the text within the brackets.
HTML Basics <html> <head> <TITLE>A Simple HTML Example</TITLE> </head> <body> <H1>HTML is Easy To Learn</H1> <P>Welcome to the world of HTML. This is the first paragraph. While short it is still a paragraph!</P> <P>And this is the second paragraph.</P> </body> </html>
HTML Basics Markup Tags HTML This element tells your browser that the file contains HTML-coded information. The file extension .html also indicates this an HTML document and must be used.
HTML Basics HEAD The head element identifies the first part of your HTML-coded document that contains the title. The title is shown as part of your browser's window
HTML Basics TITLE The title element contains your document title and identifies its content in a global context. The title is typically displayed in the title bar at the top of the browser window, but not inside the window itself.
HTML Basics BODY The second--and largest--part of your HTML document is the body, which contains the content of your document (displayed within the text area of your browser window). All other tags now come within the body tag.
HTML Basics Headings HTML has six levels of headings, numbered 1 through 6, with 1 being the largest. Headings are typically displayed in larger and/or bolder fonts than normal body text. The first heading in each document should be tagged <H1>. The syntax of the heading element is: <Hy>Text of heading </Hy> where y is a number between 1 and 6 specifying the level of the heading.
HTML Basics Paragraphs Unlike documents in most word processors, carriage returns in HTML files aren't significant. In fact, any amount of whitespace -- including spaces, linefeeds, and carriage returns -- are automatically compressed into a single space when your HTML document is displayed in a browser. A Web browser ignores this line break and starts a new paragraph only when it encounters another <P> tag
Markup languages HTML places primary emphasis on structure paragraphs, headings, lists, images, links, …. HTML places secondary emphasis on style (CSS) fonts, colours, …. HTML does not label the meaning of the text (XML)
<!DOCTYPE html PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN”> A basic document Every document should start with the following line <!DOCTYPE html PUBLIC “-//W3C//DTD HTML 4.0 Transitional//EN”> There are three required elements, defined by the tags <html>, <head> and <body> <html> <head> <title>My Home Page</title> </head> <body> <h1>Welcome</h1> </body> </html>
Basic structure elements first and last tags The HEAD section must come before the BODY section contains generic information about the document Elements specified in the HEAD section can include title, link, script, style The BODY section contains the content of the document (text, images etc) this content is structured by other tags
Block elements Block elements define sections of text, usually preceded by a blank line <p></p> - paragraph <h1></h1>...<h6></h6> - headings <pre></pre> - preserve (original format) <blockquote></blockquote> - indented text <div></div> - division used to identify a section of the document that may be subject to special formatting (for example, using stylesheets).
Paragraphs Paragraphs: <p>...</p> force a break between the enclosed text and the text surrounding it the tagged region of text may be subject to special formatting <p align="center">Here is another paragraph</p> align is an attribute of the paragraph tag center is the value of the align attribute <p>here is a piece of text that has been placed inside a paragraph</p> <p align="center">Here is another paragraph</p>
Headings Six levels of importance <h1>...<h6> Use headings to divide document into sections <html> <head> <title>Headings</title> </head> <body> <h2>Chapter 1</h2> <h3>1. Introduction</h3> This is the introduction <h3>2. Next section</h3> This is the next section <h4>2.1 A subsection</h4> This is a subsection </body> </html>
Element relationships The elements marked by tags form a hierarchy The root element is html (marked by <html>...</html>) It usually has two children: head and body each of these are further subdivided There are rules for which elements can contain other elements e.g. headers cannot contain headers see http://www.w3.org/ for a full list of rules Elements must not overlap each other we cannot have: <h1>...<a..> ... </h1>...</a> we can have: <h1>...<a..> ... </a>...</h1>
Inline descriptive elements Descriptive elements affect the appearance of text depending on how the text is described <em></em> emphasis, usually with italics <strong></strong> strong, usually with bold <cite></cite> citation, usually in italics <code></code> usually results in monotype spacing <body> A <em>fascinating</em> subject that I <strong>must</strong> understand </body>
Inline explicit style elements <boldface></boldface> <big></big> bigger font than surrounding text <small></small> smaller font than surrounding text <i></i> italics <s></s> strikethrough <sub></sub> subscripts <sup></sup> superscripts <span></span> delimits text for stylesheet control <div></div> delimits blocks of text for stylesheet control
Inline explicit style elements <font> attributes face - name of font (must be installed) "arial", "times", "verdana", "helvetica" size - absolute size (1-7), or relative to previous text "2", "5", "7", "+1", "-2"... color - hexadecimal RGB, or a named color "3399dd", "blue", "red" weight - boldness from 100, 200, ..., 900 "100", "300", "900" e.g. <font face="arial" size="+1" color="pink" weight="300">
Unordered lists Unordered lists <ul>...</ul> <li>...</li> for the list elements each item has a bullet some normal text <ul> <li>apples</li> <li>oranges</li> <li>pears</li> <li>bananas</li> </ul>
Ordered lists Ordered lists <ol>...</ol> <li>...</li> for the list elements each item has a number some normal text <ol> <li>apples</li> <li>oranges</li> <li>pears</li> <li>bananas</li> </ol>
Definition lists <dl></dl> The enclosing tags <dt></dt> The definition term <dd></dd> The definition <dl> <dt>MIME</dt> <dd> Multipurpose... </dd> <dt>FTP</dt> File transfer... <dt>TCP</dt> Transmission... </dl>
Nested lists <body> <ol> <li>apples</li> A list may contain another list The inner list is nested inside the outer list <body> <ol> <li>apples</li> <ul> <li>red</li> <li>green</li> </ul> <li>oranges</li> <li>pears</li> <li>bananas</li> </ol> </body>
<!– this is a comment --> Comments Comments are delimited by <!-- and --> <!– this is a comment --> Comments may span multiple lines <body> <!-- this is a comment --> </body>
Horizontal lines To insert a horizontal line to divide up parts of a document we use the empty tag <hr> Attributes: align, size (in pixels), width (in pixels or percentage), noshade <body> <h1>Chapter 1</h1> <hr align="center" size="3" width="50%" noshade> <h2>Introduction</h2> </body>
Special characters <body> A <em> < fascinating > </em> subject that I <strong>m u s t</strong> understand </body> Some characters such as <, >, " and & have special meanings. To prevent them being interpreted as HTML code, they must be written as follows: < > " & Blank space is normally ignored in HTML. To include a space in your document use:
Links The link (anchor) element <a>...</a> provides hypertext links between different documents (using a URL) different parts of an individual document User selection of the link (hot spot) results in retrieval and display of the designated document movement to relevant part of same document <body> The Department of <a href="http://www.doc.gold.ac.uk/index.html"> Computer Science</a> is a very .... </body>
Link with URL Example: <body> The Department of <a href="http://www.doc.gold.ac.uk/index.html"> Computer Science</a> is a very .... </body> The href attribute gives the URL of the target page The text between the tags is highlighted – selecting it activates the link
Relative addressing The previous example gave the full path name, known as the absolute address <a href="research.html">Research</a> <a href=“./pub.html">Publications</a> <a href="../../index.html">Computer Science home</a> The ‘root’ directory for the link is assumed to be the directory containing the parent page of the link
<img src="mypicture.gif" alt="my picture"> Images Images are included using the empty tag <img> Example: <img src="mypicture.gif" alt="my picture"> The src attribute specifies the file containing the image absolute or relative path names can be used (see notes for links) The alt attribute specifies the text to be displayed if the image is not viewed some users choose not to display images (for faster download) also used for compatibility with older browsers
<img src="cat.gif" height="60" width="90" align=“top” alt="cat"> Image attributes The size attributes control the size of the image <img src="cat.gif" height="60" width="90" align=“top” alt="cat"> The align attribute controls the vertical location of the image, relative to the line of text align="top" top of image aligned with top of text align="middle" centre of image aligned with centre of text align="bottom" bottom of image aligned with baseline of text The align attribute also controls the horizontal location of the image, relative to the line of text align="left" image aligned with left margin align="right" image aligned with right margin
Links with images A link element can include an image instead of text both images and text can be included if required <body> Enter my world of cats <a href="cats.html"><img src="cat.gif" height="60" width="60" align="middle" alt="cat"></a> </body>
<body bgcolor="#994422"> Colour Colours are specified with hexadecimal numbers for the red, green and blue primary colours, preceded by a “#”. To set the background colour of a web page <body bgcolor="#994422">
Colour – RGB Model #ff0000 (red), #00ff00 (green) #0000ff (blue) #ffff00 (yellow) ... #3395ab (a pastel blue)
Colour To set the colour of all text on a page <body text="#994422"> To set the colour of all text on a page In the body element, the colour of link text can be controlled with the following attributes: link for an un-visited link vlink for a visited link alink for a link that is currently selected by the mouse Example <body text="#000000" link="#0000ff">
Colour To set the colour of an individual piece of text use the font element (or preferably stylesheets – see later) <body bgcolor="#3395ab"> Text in quotes <font color="#ff0000">"such as this"</font> has a different colour </body>
Colour names Netscape and Internet Explorer allow textual names for colours instead of hexadecimal This is OK provided the page is not looked at by a browser that does not support colour names For example <body bgcolor="gray" text="black" link="blue">
<body background="tileimage.gif"> Background patterns Rather than a uniform color You can give the background of web page a pattern as follow: <body background="tileimage.gif">
Forms Server-based programs may return data to the client as a web page Client-side scripts can read input data To validate the data, prior to sending to server To use in local processing which may output web page content that is displayed on the client
Example applications Questionnaires to provide feedback on a web site e-commerce, to enter name, address, details of purchase and credit-card number request brochures from a company make a booking for holiday, cinema etc. buy a book, cd, etc obtain a map giving directions to a shop Run a database query and receive results (an important part of e-commerce)
Input types text checkbox radio (buttons) select (options) textarea password button submit reset hidden file image
The method and action attributes The method attribute specifies the way that form data is sent to the server program GET appends the data to the URL POST sends the data separately The action attribute specifies a server program that processes the form data (often as a URL) <body> <form method="POST" action="comments.php"> <h2>Tell us what you think</h2> <!-- etc --> </form> </body>
The input element: type="text" The type attribute specifies the type of user input The name attribute gives an identifier to the input data <form method="POST" action="comments.php"> <h2>Tell us what you think</h2> Name <input name="name" type="text" size="20"><br> Address <input name="address" type="text" size="30"> </form>
The input element: type="checkbox" The name attribute is used to define a set of checkboxes The value attribute identifies the individual checkbox If the checked attribute is set the box is initially checked How did you hear about this web site?<br> A friend <input type="checkbox" name=“name" value="friend"><br> Search engine <input type="checkbox" name=“name" value="engine"><br>
The input element: type="radio" Radio buttons are similar to checkboxes, but only one can be selected To select a button by default, use the checked attribute (for one button only) How did you hear about this web site?<br> A friend <input type="radio" name=“name" value="friend"><br> Search engine <input type="radio" name=“name" value="engine"><br> <!– etc -->
The input element: type="button" The name attribute uniquely identifies a button The value attribute gives a label to the button Actions can be associated with buttons using JavaScript see later Do you want to receive any further information:<br> <input type="button" name="yes" value=" Yes "> <input type="button" name="no" value=" No "><br>
The input element: type="submit/reset" clicking this button sends the form data to the program (URL) specified in the action attribute of the form type="reset" clicking this button clears all data entered so far Thank you<br> <input type="submit" name="send" value="Send"> <input type="reset" name="clear" value="Clear"><br>
The input element: type="password/file/hidden" similar to type="text" except that the input is echoed with asterisks (so not visible) type="file" provides a file dialogue box to specify a file that is sent to the server type="hidden" similar to text input, but the value attribute is used to specify data that is to be sent to the server. Nothing appears on the screen. The data might be set by a server program to keep track of the details of a particular transaction.
The textarea element Used for multi-line text input The size of the input area is specified with the cols and rows attributes Any text placed inside the element appears in the input area (this can be deleted). Please write your comments:<br> <textarea name="comments" rows="5" cols="20"> put text here </textarea>
The select element The select element provides a menu of options An option can be selected by default using the selected attribute (otherwise the first in the list is initially selected) How do you rate this site?<br> <select name="rating"> <option>Good <option selected>Bad <option>Ugly </select>
Tables Tables provide a means of organising the layout of data A table is divided into rows and columns: these specify the cells of the table
Tables <table border="1"> <tr> <th>Name</th> <td>A B Morgan</td> <td>D P Jones</td> </tr> <th>Course</th> <td>Fishing</td> <td>Sailing</td> <th>Year</th> <td>8</td> <td>5</td> </table> <table> main element <tr> table row <th> table header <td> table data
Rows and Columns <table border="1"> <tr> <th colspan="2">Name</th> <th>Course</th> <th>Year</th> </tr> <td>A B</td> <td>Morgan</td> <td rowspan="2">Fishing</td> <td>5</td> <td>D J</td> <td>Jones</td> <td>8</td> </table> Cells can span multiple columns and multiple rows with the colspan and rowspan attributes
The align and width attributes The align attribute determines the position of the text within a cell The width attribute determines the width of the row relative to the table <table border="1" align="center"> <tr> <th colspan="2" width="60%">Name</th> <th rowspan="2">Course</th> <th rowspan="2">Year</th> </tr> <th>Last</th> <th>Init.</th> <td>Morgan</td> <td>AB</td> <td>Fishing</td> <td align="center">5</td> <!– etc -->
Table attributes Table attributes Furthermore align alignment relative to the page width in pixels or percentage of page width border - width of border (pixels) cellspacing separation between cells (pixels) cellpadding - space around data inside cell (pixels) bgcolor - background colour (inside cells) Furthermore The <caption> element puts a title above the table
Table attributes <table border="3" align="center" cellspacing="6" cellpadding="6" bgcolor="cyan"> <caption> <h2>Course Data</h2> </caption> <tr> <th>Name</th> <th>Course</th> <th>Year</th> </tr> <td>A B Morgan</td> <td>Fishing</td> <td>5</td> <!– etc -->
Frames and Framesets A frameset partitions a web browser window so that multiple web documents can be displayed simultaneously. Example application: To maintain a permanently visible directory of links within your site, while also displaying one or more selected documents from the site.
Framesets <html> <head><title>Frames 1</title></head> <frameset cols="140,*"> <frame name="navF" src="navigation.html"> <frame name="mainF" src="intro.html"> </frameset> </html> The frameset element replaces the body element frameset has attributes cols or rows, defined in terms of pixels, percentage(%) or unspecified (*) this splits the window into two or more columns or rows
Frame attributes <frameset cols="140,*"> <frame name="navF" src="navigation.html"> <frame name="mainF" src="intro.html"> </frameset> The name attribute uniquely identifies the frame. It may be used as the target in an anchor (<a>) element The src attribute specifies the web page to be placed in the frame initially (it may subsequently be overwritten)
Frame attributes <frameset cols="140,*"> <frame name="navF" src="navigation.html"> <frame name="mainF" src="intro.html"> </frameset> The scrolling attribute ("auto", "yes", "no") specifies whether the frame is to have scroll bars The frameborder attribute ("0", "1") specifies whether the frame is to have a border
navigation.html The anchor tag has a target attribute takes the name of the frame used to display the information All anchors below are targeted to the "mainF" frame <html><head><title>Navigation Bar</title></head> <body><center> <a href="course.html" target="mainF">HTML Course</a><br><br> <a href="paragraph.html" target="mainF">Paragraphs</a><br> <a href="headings.html" target="mainF">Headings</a><br> <a href="ulists.html" target="mainF">Unordered lists</a><br> <a href="olists.html" target="mainF">Ordered lists</a><br> <a href="nlists.html" target="mainF">Nested lists</a><br> <a href="intro.html" target="mainF">Home</a><br> </center></body> </html>
intro.html A simple document which is initially placed in the "mainF" frame This is replaced when a user clicks on a link in the "navF" frame <html> <head><title>Internet Computing</title></head> <body> <h2>Welcome to the HTML Course</h2> <p> <h4>Please select the subject of...</h4> </p> </body> </html>
Nested framesets <html> <head><title>Frames 2</title></head> <frameset cols="140,*"> <frame name="navF" src="navigation.html"> <frameset rows="30%,70%"> <frame name="upperF" src="intro.html"> <frame name="lowerF" src="course.html"> </frameset> </html>
Noframes Some browsers cannot process frames. Alternative content should be provided using the noframes element <html> <head><title>Frames 1</title></head> <frameset cols="140,*"> <frame name="navF" src="navigation.html"> <frame name="mainF" src="intro.html"> </frameset> <noframes> <body> Something here for browsers not supporting frames </body> </noframes> </html>
Stylesheets One of the most important functions of HTML is its ability to separate the content and presentation of a web document Aspects of the document presentation include positioning on the page choice of fonts colours and backgrounds borders
Styles A style is a set of formatting instructions that can be applied to a piece of text. Styles can be defined Within a single HTML tag – Inline styles In the <head> section, and applied to the whole document – Global styles In external files, and can be applied to any document by including the URI of the file – Stylesheets
Inline styles Every tag has a style attribute This can be assigned a style definition A style definition is a list of property-value pairs a property is separated from its value by a colon property-value pairs are separated by semi-colons the list is delimited by quotation marks A property-value pair is also called a declaration Inline styles only affect the text contained in the tag <h1 style="color:#2255ff; border:ridge">Inline styles</h1>
Inline styles The heading is boxed with the text displayed in blue <body> <h1 style="color:blue; border:ridge"> Inline styles</h1> <p style="margin-left:10%; background:#ffffcc"> some text . . . some text </p> The heading is boxed with the text displayed in blue The paragraph is indented by 10% (from the left) and has a cream background
Global styles A style can be defined in the head of the document using the <style> tag The style declaration is placed inside a comment so that it can be ignored by older browsers Each style rule consists of the name of an element (selector) followed by a list of property-value pairs enclosed in curly brackets <head> <title>Styles</title> <style> <!-- h1 { color: red; border: thin groove; text-align:center; } --> </style> </head> <body> <h1>Simple styles</h1> </body>
Example <head> <style> <!-- h1 { color: red; border: thin groove; text-align:center; } p { margin-left: 10%; border: ridge; background: #ee8822; --> </style> </head> <body> <h1>Simple styles</h1> <p>some text . . . </p> </body> A global style applies to every instance of the corresponding element in the document
<link rel="StyleSheet" type="text/css" href="URL"> Stylesheets Styles can be declared in separate files called stylesheets. A stylesheet is linked to a web document by including the following line in the head section <link rel="StyleSheet" type="text/css" href="URL"> rel specifies the type of link being used href specifies a hyperlink to the stylesheet file type specifies the MIME type of the data text/css describes the “cascading style sheets” type
Multiple stylesheets The first stylesheet is included using the <link> tag Any further stylesheets have to be imported The @import command is placed inside a comment <head> <title>Stylesheets</title> <link rel="StyleSheet" type="text/css" href="http://www.abc.com/mainstyles.css"> <!– @import url(http://www.abc.com/deptstyles.css) url(mystyles.css) --> </head>
Cascading stylesheets Multiple stylesheets can be included in a document Styles defined in the first stylesheet are overridden by corresponding styles defined in the second stylesheet the stylesheets are said to cascade Example mainstyles.css – the company's stylesheet deptstyles.css – the department's stylesheet mystyles.css – the user's stylesheet If the stylesheets are included in this order, the user's style definitions will override the department styles, which in turn will override the company styles
Cascading stylesheets Different stylesheets for different media, platforms and systems Font size in CSS does not yield sam results on different screens. On Print Media 10pt size fonts are always the same size because the size of a pt is well defined. The conversion of pt to px (pixel) is different on Windows, Linux or Mac OS X platforms. Browser allow to customize layout and fonts
Style rules A style rule has two parts a selector (element name) and a set of declarations The selector associates the style rule with a HTML tag of the same name Each declaration has two parts: a property and a value For readability, each declaration should be placed on a separate line selector { property: value; }
Style rules Some properties can be given multiple values The browser first looks for the "Book Antiqua" font If this is not on the system, it looks for the Times font Last resort: the browser uses the generic serif font body { background-color: lightgreen; } h1 { color: lightgreen; background-color: blue; font-family: "Book Antiqua", Times, serif; border: thick groove #9baab2;
Properties and values Fonts font-family: <family name> [<generic family>] font-style: normal|italic|oblique font-weight: normal|bold|bolder|lighter font-size: small|medium|large|smaller|larger Backgrounds and colours color: <value> background-color: <value>|transparent background-image: URL|none
a:link, a:visited, a:active{text-decoration: none} Properties and values Text text-decoration: none|underline|overline|line-through text-transformation: none|capitalize|uppercase|lowercase text-align: left|right|center|justify text-indentation: length|percentage Example: To remove underlining on links: a:link, a:visited, a:active{text-decoration: none}
Properties and values Boxes margin: length|percentage|auto {1,4} border-width: thin|thick|medium|length {1,4} padding: length|percentage {1,4} border-color: value {1,4} border-style: none|dotted|dashed|solid|double|groove {1,4} ridge: value {1,4} width: length|percentage|auto height: length|auto
Properties and values Position location: absolute|relative|fixed absolute: relative to upper left corner of window relative: relative to the last item fixed: does not move when the page is scrolled left: distance from left border of window (pixels, %) top: distance from top border of window (pixels, %)
Classes Simple style rules change the appearance of all instances of the associated element A class is a style definition that may be applied as and when we choose if we don't want the styles, we don't have to use them Simple classes are applied to a single type of element Anonymous classes can be applied to any type of element
Simple classes </head> <style> <!-- h1.fred { color: #eeebd2; background-color: #d8a29b; border: thin groove #9baab2; } --> </style> <body> <h1 class="fred">A Simple Heading</h1> <p>some text . . . some text</p> </body>
Anonymous classes </head> <style> <!-- .fred { color: #eeebd2; background-color: #d8a29b; border: thin groove #9baab2; } --> </style> <body> <h1 class="fred">A Simple Heading</h1> <p class="fred">some text . . . some text</p> </body>
CSS Classes…cont. TD {font-face : sans-serif; font-size : 12pt} white CSS Classes…cont. grey TD {font-face : sans-serif; font-size : 12pt} .even {background-color : #FFFFFF} .odd {background-color : #CCCCCC} In your HTML code for the table: you simply reference the class to invoke the style: <td class=“even”>display this text with a white background </td> <td class=“odd”>and this text with a grey background </td>
IDs Classes specify styles for particular instances of an element IDs specify the style of a single element <head> <style> <!-- #list1 { color: blue; background: cyan; text-decoration: underline; border: thin groove red; } --> </style> </head> <body> <ul id="list1"> <li>First</li> <li>Second</li> <li>Third</li> </ul> </body> IDs allow the element to be identified by other elements on the page
<DIV> & <SPAN> are your friends <div> and <span> tags allow you define exceptions to the general rules of your body text…and they are helpful tools for document designers and web developers <div> is usually used to designate styles for block elements that should stand apart from the body text…like callout quotes. Everything inside a <div> tag takes on the <div> attributes…and you can specify classes and ids for <div> too!
Divisions and spans Rather than applying styles to an element itself, we wrap the element in a div element (usually for block elements), or a span element (usually for inline elements) Any required formatting can then be applied to the <div> or <span> element. Div and span elements become part of the document In particular, each can have class and id attributes
Divisions Styles can be applied to blocks of HTML code using div <head> <style> <!-- .myclass { color: blue; background: cyan; text-decoration: underline; border: thin groove red; } --> </style> </head> <body> <div class="myclass"> <h2>A Simple Heading</h2> <p>some text . . . </p> </div> </body> Styles can be applied to blocks of HTML code using div
Spans spans are similar to divisions <head> <style> <!-- .myclass { color: red; background: cyan; text-decoration: none; } --> </style> </head> <body> <span class="myclass"> <h2>A Simple Heading</h2> <p>some text . . . </p> </span> </body>
Layers The browser maintains a stack of layers, each containing text, images etc. The browser displays layers on top of each other (in order). The <div> tag has the following attributes z-index: the number of the layer containing the division left and top : the location (top-left corner) of the division in pixels width and height: the size of the division in pixels position: absolute or relative
Layers Layers can be manipulated using JavaScript to create Dynamic HTML pages Layers can also be used to organise page content <body> <div style="z-index:2; left:100px; top:50px; position:absolute; background-color:red; font-size:30"> <p>THIS STUFF IS ON TOP</p> </div> <div style="z-index:1; left:10px; top:10px; position:absolute; background-color:yellow; font-size:56"> <p>BACKGROUND STUFF</p></div> </body>
Summary By now you should be able to use: Tables Frames Stylesheet – CSS Inline style Embedded style External style
Typical exam question explain why is it important to separate the content from the style. what is CSS? State three ways in which styles can be used. And explain the advantages and disadvantages of each one.
Next Look at the disadvantages of html XML XHTML vs HTML DHTML Well formed vs valid xml document XHTML vs HTML DHTML
Useful sites http://www.w3schools.com/ http://www.w3schools.com/html http://www.w3schools.com/css