Web Design With CSS

By:

AMELITA M. SANTOS (Faculty, School of Computer Science, Arellano University)

What is the web? In a nutshell, the web is a whole bunch on interconnected computers talking to one another.  The computers (on the web) are typically connected by phone lines, digital satellite signals, cables, and other types of data-transfer mechanisms.  A 'data-transfer mechanism' is a nerd's way of saying: sa ying: a way to move information from point A to t o point B to point C and so on. The computers that make up the th e web can be connected all the time (24/7), or they can be connected only periodically.  The computers that are connected all the t he time are typically called a 'server'.  Servers are computers just like the th e one you're using now to read this article, with one major difference, they have a special software installed called 'server' software.

Web Design The

skill of designing hypertext presentations of  content that is delivered to an end-user through the World Wide Web.

The

process of designing Web pages, Web sites, Web applications or multimedia for the Web and may utilize multiple disciplines, such as animation, authoring, graphic design, human-computer  interaction, interaction design, photography, and search engine.

Technologies Involved   Markup

languages (such as HTML, XHTML and

XML)   Style

sheet languages (such as CSS and XSL)

  Client-side

scripting (such as JavaScript and

VBScript)   Server-side   Database

scripting (such as PHP and ASP)

technologies (such as MySQL)

  Multimedia

Silverlight)

technologies (such as Flash and



A style sheet language is a computer  language used to describe the presentation of  structured documents. • A structured document is a document whose

sections are clearly defined and categorized (also called "well-formed"). A program presenting the document can present it in different styles because the content has been categorized. 

One modern style sheet language with widespread use is CSS (Cascading Style Sheets) , which is used to style documents d ocuments written in HTML, or XHTML and other markup languages.

What is CSS??? CSS is the acronym acronym for: ‘Cascading Style Sheets’ CSS is an extension to basic HTML that allows you to style your web pages. Style sheets let you place things exactly where you want them to be on the page, using the distance in pixels from the top and the t he left of the browser b rowser window.  Styles

define how to display HTML elements

 Styles

are normally stored in Style Sheets

 External

Style Sheets can save you a lot of work

 External

Style Sheets are stored in CSS files

 Multiple

style definitions will cascade into one

Advantages of CSS CSS is an excellent addition to plain HTML. 

With plain HTML you define the colors and sizes of text and tables throughout your pages. If you want to change a certain element you will therefore have to work your way through the document and change it.

With CSS you define the colors and sizes in " styles". As you write your documents you refer to the styles. Thus, if you change a certain style it will change the look of your entire site. CSS offers much more detailed attributes than plain HTML for  defining the look and feel of your site. Finally, CSS can be written so the user will only need to download it once - in the external style sheet document. When surfing the rest of your site the CSS will be cached on the users computer, and therefore speed up the loading loadi ng time.

Things to Remember About CSS: CSS

code is simply written instructions that tells Web browsers (like FireFox and Internet Explorer) how to display things on a page.

For

example:



make text bold.



position things a page.



set the font style for a page or paragraph etc.

The

sister language to CSS is HTML: code that tells the Web browser WHAT is actually in the th e page.

HTML file

A sample HTML A simple HTML structure This is header 1 This is header 2 This is a paragraph

Using Style 

Styles are set by adding the TAG: 

This is placed in the section of your page.

CSS Syntax The

CSS syntax is made up of three parts:

1. a selector 

selector {property: value}  The

selector is normally the HTML element/tag you wish to define, the property is the attribute you wish to change, and each property can take a value.

2. a property and a value:  The

property and value are separated by a colon, and surrounded by curly braces:

body {color: black}

CSS Syntax  Note:

If the value is multiple words, put quotes around the

value: 



p {font-family: "sans serif"} Note: If you wish to specify more than one property, you must  separate each property with a semicolon. The example below  shows how to define a center aligned paragraph, with a red text  color: p {text-align:center;color:red} Note: To make the style definitions more readable, you  can describe one property on each line, like this: p { text-align: center; color: black; font-family: arial }

Grouping You can group selectors by separating separating each selector with a comma. In the example below we have grouped all the header elements. All

odd header elements will will be displayed in green text color:

h1,h3,h5 { color: green } All even header header elements will will be displayed in green text color: h2,h4,h6 { color: yellow}

The class Selector With the class selector you can define different styles for the same type of HTML element. Say that you would like to have two types of paragraphs in your document: one right-aligned paragraph, and one centeraligned paragraph. Here is how you can do it with styles: p.right {text-align: right} p.center {text-align: center} You have to use the class attribute in your HTML document: This paragraph will be rightaligned. This paragraph will be center-aligned. center-aligned.

CSS Syntax Note:

To apply more than one class per given element, the syntax is:

This is a paragraph. The paragraph above will be styled by the class "center" AND the class "bold". " bold". You

can also omit the tag t ag name in the selector to define a style that will be used by all HTML elements that have a certain class. In I n the example below, all HTML elements with class="center" will be centeraligned:

.center {text-align: center}

CSS Style In

the code below both the h1 element and the p element have class="center".

This

means that both elements will follow the rules in the ".center" selector:

This heading will be center-aligned This paragraph will also be center-aligned.

Add Styles to Elements with Particular Attributes You can also apply styles to HTML elements with particular attributes. The style rule below will match all input elements that have a type attribute with a value of "text":

input[type="text"] input[type="text"] {backgroundcolor: blue}

The ID Selector You

can also define styles for HTML elements with the id selector. The id selector s elector is defined as a #. The style rule below will match the element that has an id attribute with a value of "green": " green": #green {color: green} The

style rule below will match the p element that has an id with a value of "para1": " para1": p#para1 { text-align: center; color: red }

How to Insert a Style Sheet When a browser reads a style sheet, it will format the document according to it. There are three ways of inserting a style sheet:

1. External Style Sheet  An

external style sheet is ideal when the style is applied to many pages. With an external style sheet, you can change the look of an entire Web site by changing one file.

2. Internal Style Sheet  An

internal style sheet should be used when a single document has a unique style. You define internal styles in the head section by using the tag.

3. Inline Styles  An

inline style loses many of the advantages of style sheets by mixing content with presentation. Use this method sparingly, such as when a style is to be applied to a single occurrence of  an element.

A. External Style Sheet-1 Each page must link to the style sheet using the tag. The tag goes inside the head section: The

browser will read the style definitions from the file mystyle.css, and format the document according to it.

A. External Style Sheet-2 An external style sheet can be written in any text editor. The file should not contain any html tags. Your style sheet should be saved with a .css extension. 

An example of a style sheet file is shown below:

hr {color: sienna} p {margin-left: 20px} body {background-image: url("images/back40.gif")}

Creating External CSS file  External

style sheets allow you to set all the rules for  the entire site in one place, giving your site a consistent look across all the pages. •  You must create a text file called mystyles.css. •  Type the styles code below into the file. f ile. • Notice that this code does not have the tag in it: H2 { color:red; font-weight:900; font-family:sans-serif; }

Example

myCSS.css-- External CSS File myCSS.css

html File w/ external CSS

OUTPUT of External CSS

B. Internal Style Sheet You

define internal styles in the head section by using the tag, like this: hr {color: sienna} p {margin-left: 20px} body {background-image: url("images/ back40.gif")}

B. Internal Style Sheet Note:

A browser normally ignores unknown tags like an old browser that does not support styles, will ignore the tag, but the content of the tag will  be displayed on the page.

It is possible to prevent an old browser from displaying the content by hiding it in the HTML comment element: