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Friday, 6 December 2013

CSS : CLASS SELECTOR

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 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:

Example

.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:

Example

p.center {text-align:center;}

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:

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");}

* 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

CSS : INTERNAL STYLE SHEET

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 type="text/css">
hr {color:sienna;}
p {margin-left:20px;}
body {background-image:url("images/back40.gif");}
</style>
</head>

CSS : INLINE STYLES

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>

CSS : MULTIPLE STYLE SHEETS

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.

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

Tip: Even multiple external style sheets can be referenced inside a single HTML document.

CSS : CASCADING ORDER

Cascading order

What style will be used when there is more than one style sp

ecified 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:

1. Browser default

2. External style sheet

3. Internal style sheet (in the head section)

4. Inline style (inside an HTML element)

So, an inline style (inside an HTML element) 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 (a default value).

* 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!

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

CSS : BACKGROUND COLOR

Background Color

The background-color property specifies the background color of an element.

The background color of a page is defined in the body selector:

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"

In the example below, the h1, p, and div elements have different background colors:

Example

h1 {background-color:#6495ed;}
p {background-color:#e0ffff;}
div {background-color:#b0c4de;}

MECHANICAL,CSS,HTML

Friday, 6 December 2013

CSS : CLASS SELECTOR

CSS : EXTERNAL STYLE SHEET

CSS : INTERNAL STYLE SHEET

CSS : INLINE STYLES

CSS : MULTIPLE STYLE SHEETS

Multiple Styles Will Cascade into One

CSS : CASCADING ORDER

CSS : BACKGROUND COLOR

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