Introduction to css

Introduction
To CSS
by: Faizan Ahmed

HTML Review
► What is HTML used for?
► Give some examples of formatting tags in HTML?
► HTML is the most widely used language on the
Web
► In today’s lesson we will be discussing the
second most widely used language on the web
► Does anyone know the name of the second most
widely used language?

Lesson 1: History of CSS
► CSS was proposed in 1994 as a web styling
language. To helps solve some of the
problems HTML 4.
► CSS2 became the recommendation in 1998
by W3C
► CSS3 was started in 1998 but it has never
been completed. Some parts are still being
developed and some components work on
some browsers.

Lesson 1: What is CSS?
• CSS stands for Cascading Style Sheets
• Styles - define how to display HTML elements
• Styles are normally stored in Style Sheets
Definition:
Cascading Style Sheets (CSS) – is a rule based language
that applies styling to your HTML elements. You write
CSS rules in elements, and modify properties of those
elements such as color, background color, width, border
thickness, font size, etc.

Lesson 2: Syntax of CSS
 The CSS syntax is made up of 5 parts:
 selector
 property/value
 declaration
 declaration block
 curly braces
We will explore each part in the next slides.

Selector
 Definition: identifies the HTML elements that
the rule will be applied to, identified by the
actual element name, e.g. <body>, or by other
means such as class attribute values.
 Example:
*The selector is normally the HTML element you want to style

Declaration Block
Definition: multiple declaration lines including the
curly braces

Declaration
 Definition: Each CSS line that includes property
and value
*Each declaration consists of a property and a value.

Property & Value
 Definition: The property is the style attribute
you want to change. Each property has a value.
*Properties are separated from their respective values by colons :
*Pairs are separated from each other by semicolons ;

Curly Braces
 Definition: the curly braces contain the
properties of the element you want to
manipulate, and the values that you want to
change them to. The curly braces plus their
content is called a declaration block.
 Example:

Lesson 2 Assignment:
Let’s Create Our First CSS Page
► Open Notepad
► Type the following Code
<html>
<head>
<style type="text/css">
p {color:red; text-align:center;}
</style>
</head>
<body>
<p>Hello World!</p>
<p>This paragraph is styled with CSS.</p>
</body>
</html>
► Save Your File as css-myfirstpage.html into a new folder called CSS

Lesson 3: Class and id Selectors
 In addition to setting a style for a HTML element, CSS allows
you to specify your own selectors called "id" and "class".
id - 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":
 #para1 {text-align:center;color:red;}

Class - 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:
 .center {text-align:center;}

 In the image below what is the h1 selector an
ID or a Class?
#
.

Let’s Create A CSS Page that uses “id”
► Open Notepad
<html>
<head>
#para1
{
text-align:center;
color:red;
}
</style>
</head>
<body>
<p id="para1">Hello World!</p>
<p>This paragraph is not affected by the style.</p>
</body>
</html>
► Save Your File as css-id.html into a your folder called CSS.

Let’s Create A CSS Page that uses “class”
► Open Notepad
<html>
<head>
.center
{
text-align:center;
}
</style>
</head>
<body>
<h1 class="center">Center-aligned heading</h1>
<p class="center">Center-aligned paragraph.</p>
</body>
</html>
► Save Your File as css-class.html into a your folder called CSS.

Lesson 3 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.
► You add comments by enclosing them in
/* and */
► Comments can span several lines, and the browser will ignore these lines.
► Example:
► /* This is a basic comment it will not appear on the page*/
/* starts the comment
*/ is the end of the comment
/*This is a comment*/
p{ text-align:center; color:black; font-family:arial;}

Let’s Add A Comment
► Open Your CSS-ID example in Notepad
► Type the following Code right above the style you had written previously.
<html>
<head>
/*This is an example of how to use ID in a CSS web page*/
#para1
{
text-align:center;
color:red;
}
</style>
</head>
<body>
<p id="para1">Hello World!</p>
<p>This paragraph is not affected by the style.</p>
</body>
</html>
► Save Your File as css-comment.html into a your folder called CSS.

Lesson 4: How CSS is Applied to A Web Page
►CSS is applied to a web page using three
different methods:
 Inline style
 Internal style sheet
 External style sheet

►Inline CSS
►Applies styles directly to the elements by
adding declarations into the style
►For Example:
<p style=“color: red;”> This is a simple
paragraph and the inline style makes it
red.</p>

► Internal Style Sheet
► Applies styles to HTML by placing the CSS rules inside the tag
<style> inside the document tag <head>.
► For Example:
<head>
<title>my page</title>
<style type=“text/css”>
p{color:red}</style>
</head>
<body>
<p>this is a simple paragraph
</p>
</body>

► External CSS
► Applies styles as a separate file with a .css extension. The file is
then referenced from inside the <head> element by a link to the
file.
► For Example:
<head>
<title>my external style sheet page</title>
<link rel=“style sheet” type=“text/css” href=“my-external-
stylesheet.css”>
<body>
<p>this is a simple paragraph</p>
</body>
► You can create an external style sheet in your text editor.

► What style sheet is best?
► Web developers rarely use inline CSS. Since they prefer
to not mix content with presentation. And it is not
efficient since you have to declare the style individually
for every component.
► Internal and External style sheets are more popular
because you can style multiple elements with one rule.
► External style sheets are best because they allow you to
save all the style information on a separate file from the
content. You can then modify a style for a site and it will
update all of the pages in a site.

►CSS Colors
►In the previous lesson you have seen a few
CSS styles that included color like: <p
style=“color: red;”>
►There are a few ways that you can set
colors in CSS:
Keywords, Hex values, RGB, HSL(a)
Lesson 5: Colors and Formatting in CSS

► CSS Colors: Keywords
► Using the keywords like: red, fuchsia, yellow,
blue, green you can specify what color you would
like the CSS rule to display.
► For example:
► p{color:red}
► h2{color:yellow}
► There are 17 of these keyword colors you can
use in CSS.

Keyword Color Hex
aqua #00ffff
black #000000
blue #0000ff
fuchsia #ff00ff
gray #808080
green #008000
lime #00ff00
maroon #800000
navy #000080
olive #808000
orange (added in CSS 2.1) #ffa500
purple #800080
red #ff0000
silver #c0c0c0
teal #008080
white #ffffff
yellow #ffff00

► Computers are capable of displaying a lot more
than 17 colors.
► In fact they can display approximately 16.7
million colors!
► Hex Values (hex is short for hexadecimal) are the
most common way of specifying colors for web
pages. (see hex# in the previous chart)
► For example:
p{color: #000000;}
/*This is equivalent to the keyword black*/

►Hex numbers - has 16 possible values
►0 to 9 then A to F. Which gives you 16
values.
►RGB (Red Green Blue) has the possibility of
256 colors for each (16x16)
►(R)256 x (G)256 x (B)256 = 16,777,216 or
16.7 million color values
►CSS example: h1{color: #000000;}

► RGB (a) can also help specify colors in CSS RGB
stands for Red Green Blue
► You can specify RGB in either whole numbers or
percentages
► CSS example: h1{color: rgb(0,0,0) }
/*this color is equivalent to #000000 or black */
► You use numbers from 0 to 255 which covers the
256 color range.
► More examples can be found at:
http://www.w3schools.com/css/css_colors.asp

► RGB (a) can also help specify colors in CSS RGB stands
for Red Green Blue. The “a” stands for alpha but we will
learn about that in another lesson.
► You can specify RGB in either whole numbers or
percentages
► CSS example: h1{color: rgb(0,0,0) }
/*this color is equivalent to #000000 or black */
► You use numbers from 0 to 255 which covers the 256
color range.
► More examples can be found at:
http://www.w3schools.com/css/css_colors.asp

► HSL (a) - Hue Saturation Lightness
► Similar to RGB but based on saturation and
lightness of a color
► The “a” stands for alpha but we will learn about
that in another lesson.
► CSS example: h1{color: hsl(0,100%,40%) }
► HSL accepts a number between 0 to 360 in value
► HSL also accepts percentage between 0-100%

CSS Using Color
► Open Your CSS-ID example in Notepad
► Type the following Code right above the style you had written previously.
<html>
<body>
<p style="background-color:#FFF111">
Color set by using hex value
</p>
<p style="background-color:rgb(0,255,0);">
Color set by using rgb value
</p>
<p style="background-color:red">
Color set by using color name
</p>
</body>
</html>
► Save Your File as css-color.html into your folder called CSS

The End
►Essential Questions Review
by: Faizan Ahmed
mailtofaizanahmed@gmail.com
Facebook.com/pakifa

Introduction to css

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