basic programming language AND HTML CSS JAVApdf

CHAPTER 3
Cascading style sheet
(CSS)
1

Introduction to CSS
• One of the challenges you have when creating Web pages is positioning
elements exactly where you want them to appear on each page.
• A Web page has no internal x-y coordinate system to which you can refer when
inserting text, images, and other objects.
• In Chapter 2 of this course, you learned how to use an HTML table to create a
grid of cells that hold your Web page elements in place.
• Unfortunately, using invisible tables for page layout complicates your Web
page HTML by adding tags (at least two for each row and column in the table).
• Moreover, hidden tables make your Web page harder to maintain. Suppose,
for example, that you want to add a picture or some text at a specific location
on the page.
• To do so often requires that you recode all or a portion of the layout table to
get a new cell into place where you want the additional content to go.
2

Cascading style sheet (CSS)
• Cascading Style Sheets (CSS) is a simple mechanism for adding style (e.g., fonts,
colors, and spacing) to Web documents.
• It is a style sheet language used for describing the look and formatting of a document
written in a markup language.
• CSS is designed primarily to enable the separation of document content from document
presentation, including elements such as the layout, colors, and fonts.
• This separation can
 Improve content accessibility,
 provide more flexibility and control in the specification of presentation
characteristics,
 enable multiple pages to share formatting, and
 reduce complexity and repetition in the structural content (such as by allowing
for tableless web design).
3

Cont.…
• CSS specifies a priority scheme to determine which style rules apply if more
than one rule matches against a particular element.
• In this so-called cascade, priorities or weights are calculated and assigned to
rules, so that the results are predictable.
• The CSS specifications are maintained by the World Wide Web
Consortium (W3C).
• Styles were added to HTML 4.0 to solve a problem
• External Style Sheets can save a lot of work
• External Style Sheets are stored in CSS files
4

Cont.…
Example
body
{
background-color:#d0e4fe;
}
h1
{
color:orange;
text-align:center;
}
p
{
font-family:"Times New Roman";
font-size:20px;
}
5

cont. …
 Styles Solved a Big Problem
• HTML was never intended to contain tags for formatting a document.
• HTML was intended to define the content of a document, like:
<h1>This is a heading</h1>
<p>This is a paragraph.</p>
• When tags like <font>, and color attributes were added to the HTML 3.2
specification, it started a nightmare for web developers.
• Development of large web sites, where fonts and color information were added to
every single page, became a long and expensive process.
• To solve this problem, the World Wide Web Consortium (W3C) created CSS.
• In HTML 4.0, all formatting could be removed from the HTML document, and stored
in a separate CSS file.
• All browsers support CSS today.
6

Cont.…
 CSS Saves a Lot of Work!
• CSS defines HOW HTML elements are to be displayed.
• Styles are normally saved in external .css files.
• External style sheets enable you to change the appearance and
layout of all the pages in a Web site, just by editing one single file!
 CSS Syntax
• A CSS rule has two main parts: a selector, and one or more
declarations:
• The selector is normally the HTML element you want to style.
• Each declaration consists of a property and a value.
• The property is the style attribute you want to change.
• Each property has a value.
• CSS declaration always ends with a semicolon, and declaration
groups are surrounded by curly brackets:
7

Cont…
• To make the CSS more readable, you can put one
declaration on each line.
CSS Comments
• Comments are used to explain your code, and may help
you when you edit the source code at a later date.
• Comments are ignored by browsers.
• A CSS comment begins with "/*", and ends with "*/",
like this:
• /*This is a comment*/
p
{
text-align:center;
/*This is another comment*/
color:black;
font-family:arial;
} 8

Cont…
 CSS Id and Class
The id and class Selectors
• In addition to setting a style for a HTML element, CSS allows you to specify your own selectors called "id"
and "class".
 The id Selector
• The id selector is used to specify a style for a single, unique element.
• The id selector uses the id attribute of the HTML element, and is defined with a "#".
• Do NOT start an ID name with a number!
• The style rule below will be applied to the element with id="para1":
• #para1
{
text-align:center;
color:red;
}
9

Cont…
 The class Selector
• The class selector, unlike the id selector, is used to specify a
style for a group of elements
• This allows you to set a particular style for many HTML
elements with the same class.
• The class selector uses the HTML class attribute, and is
defined with a "."
• In the example below, all HTML elements with class="center"
will be center-aligned:
• Do NOT start a class name with a number!
• .center {text-align: center;}
• You can also specify that only specific HTML elements should
be affected by a class.
• In the example below, all p elements with class="center" will
be center-aligned:
• p.center {text-align:center;}
10

CSS How To...
• When a browser reads a style sheet, it will format
the document according to it.
• There are three ways of inserting a style sheet:
– External style sheet.
– Internal style sheet.
– Inline style.
 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.
• Each page must link to the style sheet using the
<link> tag.
11

Cont…
• The <link> tag goes inside the head section:
<head>
<link rel="stylesheet" type="text/css" href="mystyle.css">
</head>
• An external style sheet can be written in any text editor.
• The file should not contain any html tags.
• Style sheet should be saved with a .css extension.
Example:
hr {color:sienna;}
p {margin-left:20px;}
body {background-image:url("images/background.gif");}
• Do not add a space between the property value and the
unit (such as margin-left:20 px).
• The correct way is: margin-left:20px
12

Cont…
 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 of
an HTML page, by using the <style> tag, like this:
• <head>
<style>
hr {color:sienna;}
p {margin-left:20px;}
body {background-
image:url("images/background.gif");}
</style>
</head> 13

Cont…
Inline Styles
• An inline style loses many of the advantages of style
sheets by mixing content with presentation.
• Use this method sparingly!
• To use inline styles you use the style attribute in the
relevant tag.
• The style attribute can contain any CSS property.
• The example shows how to change the color and the
left margin of a paragraph:
<p style="color:sienna;margin-left:20px;">This is a
paragraph.</p>
14

Cont…
 Multiple Style Sheets
• If some properties have been set for the same selector in different
style sheets, the values will be inherited from the more specific style
sheet.
• For example, an external style sheet has these properties for the h3
selector:
h3
{
color:red;
text-align:left;
font-size:8pt;
}
• And an internal style sheet has these properties for the h3 selector:
h3
{
text-align:right;
font-size:20pt;
}
15

Cont…
• If the page with the internal style sheet also links to the
external style sheet the properties for h3 will be:
color:red;
text-align:right;
font-size:20pt;
• The color is inherited from the external style sheet and
the text-alignment and the font-size is replaced by the
internal style sheet.
Multiple Styles Will Cascade into One
• Styles can be specified:
– inside an HTML element
– inside the head section of an HTML page
– in an external CSS file
– Even multiple external style sheets can be referenced inside a
single HTML document.
16

Cont…
 Cascading order
• What style will be used when there is more than one style
specified for an HTML element?
• Generally speaking we can say that all the styles will
"cascade" into a new "virtual" style sheet by the following
rules, where number four has the highest priority:
– Browser default
– External style sheet
– Internal style sheet (in the head section)
– Inline style (inside an HTML element)
• So, an inline style has the highest priority, which means
that it will override a style defined inside the <head> tag, or
in an external style sheet, or in a browser.
• Note: If the link to the external style sheet is placed after
the internal style sheet in HTML <head>, the external style
sheet will override the internal style sheet!
17

Cont…
 CSS Background
• CSS background properties are used to define the
background effects of an element.
• CSS properties used for background effects:
– background-color
– background-image
– background-repeat
– background-attachment
– background-position
– Background Color
• The background-color property:
– specifies the background color of an element.
– defined in the body selector.
18

Cont…
Example
• body {background-color:#b0c4de;}
• With CSS, a color is most often specified by:
– a HEX value - like "#ff0000"
– an RGB value - like "rgb(255,0,0)"
– a color name - like "red“
19

Cont…
 Background Image property
• specifies an image to use as the background of an
element.
• By default, the image is repeated so it covers the
entire element.
• The background image for a page can be set like
this:
Example
body {background-image: url(“60_small.jpg");}
• Background Image - Repeat Horizontally or
Vertically
– By default, the background-image property repeats an
image both horizontally and vertically.
20

Cont…
Example
• body
{
background-image: url(" 60_small.jpg ");
}
• If the image is repeated only horizontally (repeat-
x), the background will look better.
Example
• body
{
background-image: url(" 60_smamll.jpg ");
background-repeat: repeat-x;
}
21

Cont…
 Background Image - Set position and no-repeat
• Note: When using a background image, use an image that
does not disturb the text
• Showing the image only once is specified by the
background-repeat property:
Example
• body
{
background-image:url(“60_small.png");
background-repeat:no-repeat;
}
• In the example above, the background image is shown in
the same place as the text.
• We want to change the position of the image, so that it does
not disturb the text too much.
• The position of the image is specified by the background-
position property: 22

Cont…
Example
• body
{
background-image:url(" 60_smamll.jpg ");
background-repeat:no-repeat;
background-position:right top;
}
• Background - Shorthand property
– there are many properties to consider when dealing with
backgrounds.
– To shorten the code, it is also possible to specify all the
properties in one single property. This is called a shorthand
property.
– The shorthand property for background is simply
"background":
23

Cont…
Example
• body {background:#ffffff url("img_tree.png") no-
repeat right top;}
• When using the shorthand property the order of
the property values is:
– background-color
– background-image
– background-repeat
– background-attachment
– background-position
• It does not matter if one of the property values is
missing, as long as the ones that are present are in
this order.
24

Cont…
 background-attachment
• If a background image is specified, this property specifies
whether it is fixed with regard to the viewport ('a window
or other viewing area on the screen') or scrolls along with
the containing block ('scroll').
• Possible values are fixed, scroll, inherent
body
{
background: red url(“60_small.jpg");
background-repeat: no-repeat;
background-attachment: fixed;
}
25

All CSS Background Properties
Property Description
background Sets all the background properties in one declaration
background-attachment Sets whether a background image is fixed or scrolls with the rest
of the page
background-color Sets the background color of an element
background-image Sets the background image for an element
background-position Sets the starting position of a background image
background-repeat Sets how a background image will be repeated
26

CSS Text
 TEXT FORMATTING
 Text Color
• The color property is used to set the color of the text.
• With CSS, a color is most often specified by:
– a HEX value - like "#ff0000"
– an RGB value - like "rgb(255,0,0)"
– a color name - like "red"
• Look at CSS Color Values on the net for a complete list of
possible color values.
• The default color for a page is defined in the body
selector.
Example
body {background-color:blue;}
h1 {color:#00ff00;}
h2 {color:rgb(255,0,0);} 27

 Text Alignment
• The text-align property is used to set the horizontal
alignment of a text.
• Text can be centered, or aligned to the left or right,
or justified.
• When text-align is set to "justify", each line is
stretched so that every line has equal width, and
the left and right margins are straight (like in
magazines and newspapers).
Example
• h1 {text-align:center;}
p.date {text-align:right;}
p.main {text-align:justify;}
28

 Text Decoration
• The text-decoration property is used to set or remove
decorations from text.
• The text-decoration property is mostly used to remove
underlines from links for design purposes:
Example
• a {text-decoration:none;}
• It can also be used to decorate text:
Example
• h1 {text-decoration:overline;}
h2 {text-decoration:line-through;}
h3 {text-decoration:underline;}
29

• The text-transform property is used to specify uppercase
and lowercase letters in a text.
• It can be used to turn everything into uppercase or
lowercase letters, or capitalize the first letter of each word.
p.uppercase {text-transform:uppercase;}
p.lowercase {text-transform:lowercase;}
p.capitalize {text-transform:capitalize;}
Text Indentation
• The text-indent property is used to specify the indentation of
the first line of a text.
p {text-indent:50px;}
30
 Text Transformation

 CSS Font
 CSS Font Families
• In CSS, there are two types of font family names:
• generic family - a group of font families with a similar look (like
"Serif" or "Monospace")
• font family - a specific font family (like "Times New Roman" or
"Arial")
31
Generic family Font family Description
Serif Times New Roman
Georgia
Serif fonts have small
lines at the ends on
some characters
Sans-serif Arial
Verdana
"Sans" means without -
these fonts do not have
the lines at the ends of
characters
Monospace Courier New
Lucida Console
All monospace
characters have the
same width

Cont…
Font Family
• The font family of a text is set with the font-family
property.
• The font-family property should hold several font names as
a "fallback" system.
• If the browser does not support the first font, it tries the
next font.
• Start with the font you want, and end with a generic family,
to let the browser pick a similar font in the generic family,
if no other fonts are available.
• Note: If the name of a font family is more than one word, it
must be in quotation marks, like: "Times New Roman".
• More than one font family is specified in a comma-
separated list:
p{font-family:"Times New Roman", Times, serif;}
32

Cont.…
 Font Style
• The font-style property is mostly used to specify italic text.
• This property has three values:
– normal - The text is shown normally
– italic - The text is shown in italics
– oblique - The text is "leaning" (oblique is very similar to italic, but less
supported)
p.normal {font-style:normal;}
p.italic {font-style:italic;}
p.oblique {font-style:oblique;}
 Font Size
• The font-size property sets the size of the text.
– Absolute size:
• Sets the text to a specified size
• Does not allow a user to change the text size in all browsers (bad for
accessibility reasons)
• Absolute size is useful when the physical size of the output is known
– Relative size:
• Sets the size relative to surrounding elements
• Allows a user to change the text size in browsers 33

34
Font Sets all the font properties in one declaration
font-family Specifies the font family for text
font-size Specifies the font size of text
font-style Specifies the font style for text
font-variant
Specifies whether or not a text should be displayed in a
small-caps font
font-weight Specifies the weight of a font
All CSS Font Properties

 CSS Links
 Styling Links
• Links can be styled with any CSS property (e.g.
color, font-family, background, etc.).
• In addition, links can be styled differently depending
on what state they are in.
• The four links states are:
– a:link - a normal, unvisited link
– a:visited - a link the user has visited
– a:hover - a link when the user mouses over it
– a:active - a link the moment it is clicked
• When setting the style for several link states, there
are some order rules:
a:hover MUST come after a:link and a:visited
a:active MUST come after a:hover
35

cont..
 Common Link Styles
 Text Decoration
• The text-decoration property is mostly used to remove
underlines from links:
a: link { text-decoration: none;}
a:visited{ text-decoration: none; }
a:active { text-decoration: underline;}
 Background Color
• The background-color property specifies the background color for
links:
a:link { background-color: #B2FF99;}
a:visited { background-color: #FFFF85;}
a:hover { background-color: #FF704D;}
a:active { background-color: #FF704D; }
36

 CSS Lists
• The CSS list properties allow you to set different list
item markers for :
• ordered lists
• unordered lists
– Set an image as the list item marker
• With CSS, lists can be styled further, and images can
be used as the list item marker.
 Different List Item Markers
• The type of list item marker is specified with the list-
style-type property:
ul.a { list-style-type: circle; }
ul.b { list-style-type: square; }
ol.c { list-style-type: upper-roman; }
ol.d { list-style-type: lower-alpha; } 37

cont….
An Image as the List Item Marker
• The list-style-image property is used to specify an
image as the list item marker :
ul { list-style-image: url('sqpurple.gif');}
 All CSS List Properties
38
list-style Sets all the properties for a list in one declaration
list-style-image Specifies an image as the list-item marker
list-style-position
Specifies if the list-item markers should appear
inside or outside the content flow
list-style-type Specifies the type of list-item marker

 CSS Tables
• The look of an HTML table can be greatly
improved with CSS.
 Table Borders
• To specify table borders in CSS, use the border
property.
table, th, td { border: 1px solid black; }
 Collapse Borders
• The border-collapse property sets whether the
table borders are collapsed into a single border or
separated:
table { border-collapse: collapse;}
table, th, td { border: 1px solid black;}
39

Cont…..
Table Width and Height
• Width and height of a table is defined by the width and height
properties.
table {width: 100%;}
th {height: 50px;}
Table Text Alignment
• The text in a table is aligned with the text-align and vertical-align
properties.
• The text-align property sets the horizontal alignment, like left, right,
or center.
td { text-align: right; }
• The vertical-align property sets the vertical alignment, like top,
bottom, or middle:
td { height: 50px;
vertical-align: bottom;}
40

Cont...
Table Padding
• To control the space between the border and content in
a table, use the padding property on td and th elements:
td { padding: 15px; }
Table Color
• The example below specifies the color of the borders,
and the text and background color of th elements:
table, td, th {bor der: 1px solid green; }
th { background-color: green;
color: white; }
41

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