cdocumentsandsettingsstudentdesktopnewfolderhtmlcss-100220030010-phpapp01.pdf

CSS(Cascading Style Sheets )
CSS stands for Cascading Style
Sheets
Styles define how to display HTML
elements

CSS has various levels and profiles. Each level of CSS
builds upon the last, typically adding new features and
typically denoted as CSS1, CSS2, and CSS3.
The first CSS specification to become an official W3C
Recommendation is CSS level 1, published in December
1996
CSS level 2 was developed by the W3C and published as
a Recommendation in May 1998. A superset of CSS1,
CSS2 includes a number of new capabilities like absolute,
relative, and fixed positioning of elements and z-index, the
concept of media types etc.
CSS 3
CSS level 3 is currently under development. The W3C
maintains a CSS3 progress report.

 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!

Understanding Style Rules
 A Style Rule
Style Rule is composed of two parts: a
selector and a declaration.
TH {color: red;}.
 The Selector
Selector indicates the element to which the
rule is applied.
 The Declaration
Declaration determines the property values
of a selector.
Selector
Declaration

 The Property
Property specifies a characteristic, such as
color, font-family, position, and is followed by a
colon (:).
 The Value
Value expresses specification of a property,
such as red for color, arial for font family, 12 pt
for font-size, and is followed by a semicolon (;).
P {color: red;}
Property Value

 CSS declarations always ends with a semicolon, and declaration groups are
surrounded by curly brackets:
 p {color:red;text-align:center;}To make the CSS more readable, you can put one
declaration on each line, like this:
 Example
 p
{
color:red;
text-align:center;
}
CSS Comments
 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;
}

 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
"#".
 The style rule below will be applied to the element with id="para1":
 Example
 #para1
{
text-align:center;
color:red;
}

The class Selector
 The class selector is used to specify a style for a group of elements. Unlike
the id selector, the class selector is most often used on several elements.
 This allows you to set a particular style for any 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:
 Example
 .center
 {
 text-align:center;
 }
 In the example below, all p elements with class="center" will be center-
aligned:
 Example
 p.center {text-align:center;}

Three Ways to Insert CSS
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. 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. Your style sheet should be saved with a .css extension. An example of a style
sheet file is shown below:
hr {color:red;}
p {margin-left:20px;}
body {background-image:url("images/back40.gif");}

Internal Style Sheet
An internal style sheet should be used when a single
document has a unique style.
<head>
<style type="text/css">
hr {color:red;}
p {margin-left:20px;}
body {background-image:url("images/back40.gif");}
</style>
</head>

Inline Styles
<p style="color:red;margin-left:20px">This is a paragraph.</p>
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;
}
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.

 More examples
 body {background-color:#b0c4de;}
h1 {background-color:#6495ed;}
p {background-color:#e0ffff;}
div {background-color:#b0c4de;}
 body {background-image:url('paper.gif');}
 body
{
background-image:url('gradient2.png');
background-repeat:repeat-x;
}

body
{
background-image:url('img_tree.png');
background-repeat:no-repeat;
}


 body
{
background-image:url('img_tree.png');
background-repeat:no-repeat;
background-position:top right;
}
in short it can be written as:
 body {background:#ffffff url('img_tree.png') no-repeat
top right;}

body {color:blue;}
h1 {color:#00ff00;}
h2 {color:rgb(255,0,0);}
h1 {text-align:center;}
p.date {text-align:right;}
p.main {text-align:justify;}
A
{
text-decoration:none;
}
p.uppercase {text-transform:uppercase;}
p.lowercase {text-transform:lowercase;}
p.capitalize {text-transform:capitalize;}
p {
text-indent:50px;}

 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.
 p{font-family:"Times New Roman", Times,
serif;}

 p.normal {font-style:normal;}
p.italic {font-style:italic;}
p.oblique {font-style:oblique;}
 h1 {font-size:40px;}
h2 {font-size:30px;}
p {font-size:14px;}

 Set Font Size With Em
 To avoid the resizing problem with Internet Explorer,
many developers use em instead of pixels.
 The em size unit is recommended by the W3C.
 1em is equal to the current font size. The default text
size in browsers is 16px. So, the default size of 1em
is 16px.
 The size can be calculated from pixels to em using
this formula: pixels/16=em
 Example
 h1 {font-size:2.5em;} /* 40px/16=2.5em */
h2 {font-size:1.875em;} /* 30px/16=1.875em */
p {font-size:0.875em;} /* 14px/16=0.875em */

 Styling Links
 Links can be style with any CSS property (e.g. color, font-family, background-color).
 Special for links are that they 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
 Example
 a:link {color:#FF0000;} /* unvisited link */
a:visited {color:#00FF00;} /* visited link */
a:hover {color:#FF00FF;} /* mouse over link */
a:active {color:#0000FF;} /* selected link */
 a:link {text-decoration:none;}
a:visited {text-decoration:none;}
a:hover {text-decoration:underline;}
a:active {text-decoration:underline;}
 a:link {background-color:#B2FF99;}
a:visited {background-color:#FFFF85;}
a:hover {background-color:#FF704D;}
a:active {background-color:#FF704D;}

 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;}
 ul
{
list-style-image: url('sqpurple.jpg');
}

 table, th, td
{
border: 1px solid black;
}

table,th, td
{
border: 1px solid black;
}
td
{
height:50px;
vertical-align:bottom;
}
td
{
padding:15px;
}
table, td, th
{
border:1px solid green;
}
th
{
background-color:green;
color:white;
}

 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
div.ex
{
width:220px;
padding:10px;
border:5px solid gray;
margin:0px;
}
</style>
</head>

 <style>
 .contentBox
 { display:block; border-width: 1px; border-
style: solid; border-color: 000; padding:5px;
margin-top:5px; width:200px; height:50px;
overflow:scroll
 }
 </style>
 <div class="contentBox"> Why do I call
them "CSS Scrollbars"?
 </div>

 p
{
border-top-style:dotted;
border-right-style:solid;
border-bottom-style:dotted;
border-left-style:solid;
}

 <html>
 <head>
 <style type="text/css">
 p
 {
 background-color:yellow;
 }
 p.padding
 {
 padding-top:25px;
 padding-bottom:25px;
 padding-right:50px;
 padding-left:50px;
 }
 </style>
 </head>
 <body>
 <p>This is a paragraph with no specified padding.</p>
 <p class="padding">This is a paragraph with specified paddings.</p>
 </body>
 </html>

 <html>
 <head>
 h1,h2,p
 {
 color:green;
 }
 </style>
 </head>
 <body>
 <h1>Hello World!</h1>
 <h2>Smaller heading!</h2>
 <p>This is a paragraph.</p>
 </body>
 </html>

 <html>
 <head>
 p
 {
 color:blue;
 text-align:center;
 }
 .marked p
 {
 color:white;
 }
 </style>
 </head>
 <body>
 <p>This is a blue, center-aligned paragraph.</p>
 <div class="marked">
 <p>This p element should not be blue.</p>
 </div>
 </body>
 </html>

<html>
<head>
h1.hidden {visibility:hidden;}
</style>
</head>
<body>
<h1>This is a visible heading</h1>
<h1 class="hidden">This is a hidden heading</h1>
<p>Notice that the hidden heading still takes up space.</p>
</body>
</html>
O/P
This is a visible heading
Notice that the hidden heading still takes up space.

 <html>
 <head>
 img
 {
 position:absolute;
 left:0px;
 top:0px;
 z-index:-1;
 }
 </style>
 </head>
 <body>
 <h1>This is a heading</h1>
 <img src=“mitrc.jpg" width="100"
height="40" />
 <p style=“color:red”>Because the
image has a z-index of -1, it will be
placed behind the text.</p>
 </body>
 </html>
This is a headin
Because the image has a z-index of -1, it will be placed
behind the text

 Advantages of CSS
 CSS saves time
When most of us first learn HTML, we get taught to set the font face, size,
colour, style etc every time it occurs on a page. This means we find
ourselves typing (or copying & pasting) the same thing over and over again.
With CSS, you only have to specify these details once for any element. CSS
will automatically apply the specified styles whenever that element occurs.
 Pages load faster
Less code means faster download times.
 Easy maintenance
To change the style of an element, you only have to make an edit in one
place.
 Superior styles to HTML
CSS has a much wider array of attributes than HTML.
 Disadvantages of CSS
 Browser compatibility
Browsers have varying levels of compliance with Style Sheets. This means
that some Style Sheet features are supported and some aren't. To confuse
things more, some browser manufacturers decide to come up with their own
proprietary tags.

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