Introduction to CSS by programmerblog.net

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Cascading Style Sheets(CSS)

• Introduction to CSS By Programme Blog
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• What is CSS?
• CSS stands for Cascading Style Sheets
• Styles define how to display HTML elements
• 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.
• HTML was never intended to contain tags for
  formatting a document.
• HTML was intended to define the content of a
  document, like
• lth1gtThis is a headinglt/h1gt
• ltpgtThis is a paragraph.lt/pgt
• When tags like ltfontgt, and color attributes were
  added to the HTML 3.2 specification.
• 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.
• CSS Syntax
• A CSS rule has two main parts a selector, and
  one or more declarations

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• CSS declarations always ends with a semicolon,
  and declaration groups are surrounded by curly
  brackets
• p colorred text-aligncenter
• p colorred
  text-aligncenter

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• The id and class Selectors
• The id Selector
• The id selector is used to specify a style for a
  single, unique element.
• The style rule below will be applied to the
  element with id"para1"
• The id selector uses the id attribute of the HTML
  element, and is defined with a "".
• para1 text-aligncenter
  colorred
• Note Do NOT start an ID name with a number! It
  will not work in Mozilla/Firefox.
• 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-aligncenter

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• 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-aligncenter
• Note Do NOT start a class name with a number!
  This is only supported in Internet Explorer.

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• Where CSS Fits In Page
• Three Ways to Insert CSS
• 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 ltlinkgt tag. The ltlinkgt
  tag goes inside the head section
• ltheadgt ltlink rel"stylesheet"
  type"text/css" href"mystyle.css" /gtlt/headgt

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• 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 colorsienna p
  margin-left20px body background-imageur
  l("images/back40.gif")
• 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 ltstylegt tag, like this
• ltheadgtltstyle type"text/css"gt hr
  colorsienna p
  margin-left20px body
  background-imageurl("images/back40.gif")
  lt/stylegtlt/headgt
• Inline Styles
• An inline style loses many of the advantages of
  style sheets by mixing content with presentation.
  Use this method sparingly!

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• 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
• ltp style"colorsiennamargin-left20px"gtThis is
  a paragraph.lt/pgt
• 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 colorred text-alignleft font-size8pt
  And an internal style sheet has these
  properties for the h3 selector
• h3 text-alignright font-size20pt
• If the page with the internal style sheet also
  links to the external style sheet the properties
  for h3 will be
• colorredtext-alignrightfont-size20pt

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• 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 (inside an HTML element) has
  the highest priority, which means that it will
  override a style defined inside the ltheadgt tag,
  or in an external style sheet, or in a browser (a
  default value).

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• CSS Styling
• 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
• name - a color name, like "red"
• RGB - an RGB value, like "rgb(255,0,0)"
• Hex - a hex value, like "ff0000"
• h1 background-color6495ed p
  background-colore0ffff div
  background-colorb0c4de
• body background-imageurl('bgdesert.jpg')
• background-repeatno-repeat OR repeat-x OR
  repeat-y
• Short - Hand for Background
• body backgroundffffff url('img_tree.png')
  no-repeat right top

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• Text Color
• body colorblue
• Text Alignment
• h1 text-aligncenter
• Text Decoration
• The text-decoration property is mostly used to
  remove underlines from links for design purposes.
• a text-decorationnone
• Text Transformation
• Text Indentation
• The text-indentation property is used to specify
  the indentation of the first line of a text.
• p text-indent50px
• CSS- FONT

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• 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")
• p font-family"Times New Roman", Times, serif
  
• p.normal font-stylenormal
• h1 font-size40px
• Styling Links
• Links can be styled with any CSS property (e.g.
  color, font-family, background, etc.).
• The four links states are
• alink - a normal, unvisited link
• avisited - a link the user has visited
• ahover - a link when the user mouses over it
• aactive - a link the moment it is clicked
• alink colorFF0000       /
  unvisited link /avisited color00FF00
    / visited link /ahover colorFF00FF
    / mouse over link /aactive
  color0000FF   / selected link /
• avisited text-decorationnone

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• CSS Tables
• Table Borders
• To specify table borders in CSS, use the border
  property.
• table, th, td border 1px
  solid black
• Table will have double borders. This is because
  both the table, th, and td elements have separate
  borders.
• Collapse Borders
• The border-collapse property sets whether the
  table borders are collapsed into a single border
  or separated tableborder-collapsecollapse
  table,th, tdborder 1px solid black
• Table Width and Height
• Width and height of a table is defined by the
  width and height properties.
• table width100 th
  height50px

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• Table Text Alignment
• The text in a table is aligned with the
  text-align and vertical-align properties.
• td text-alignright
• Table Color Table Padding
• td padding15px
• table, td, thborder1px solid
  greenthbackground-colorgreencolorwhite
  

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