cascading style sheets chapter four. what are they? a set of style rules that tell the web browser...

Cascading Style SheetsCascading Style Sheets

Chapter FourChapter Four

What are they?What are they?

A set of style rules that tell the web A set of style rules that tell the web browser how to present a web page or browser how to present a web page or document.document.Cascading Style SheetsCascading Style Sheets– Standard set by the W3C for managing the Standard set by the W3C for managing the

formatting information of HTML documentsformatting information of HTML documents– A single piece of formatting information is A single piece of formatting information is

called a called a stylestyle– CSS separates document content from its CSS separates document content from its

appearanceappearance

Using Style Sheets - ConUsing Style Sheets - Con

Sites need much more planning for Sites need much more planning for effective useeffective useLearning curve can be steepLearning curve can be steepMuch more testing required in all Much more testing required in all possible browserspossible browsers

A Brief History of HTML and A Brief History of HTML and CSSCSS

Separating Style from StructureSeparating Style from Structure– Mixing display instructions and structural Mixing display instructions and structural

information:information:Adds to complexity of codeAdds to complexity of code

Inefficient mechanism for handling display Inefficient mechanism for handling display characteristics of multi-page Web sitescharacteristics of multi-page Web sites

Limits cross-platform compatibility of contentLimits cross-platform compatibility of content– limits diversity of web deviceslimits diversity of web devices

CONTENTSTYLE

What are they?What are they?

Web page

CSS styles are created CSS styles are created using name/value pairs using name/value pairs separated by a colonseparated by a colon

Name portion refers to Name portion refers to a specific CSS a specific CSS

style attribute known style attribute known as a as a propertyproperty

Sample Style SheetSample Style Sheet

What Can I Change?What Can I Change?

Font Stuff - size, family, weight, variant (small caps) Font Stuff - size, family, weight, variant (small caps) white space, letter spacing, line heightwhite space, letter spacing, line height

Spacing - margin, padding, Spacing - margin, padding,

Alignment - right, left, center, top, bottom, centerAlignment - right, left, center, top, bottom, center

Color - font, background, hoverColor - font, background, hover

Text - alignment, indent, decorationText - alignment, indent, decoration

Containers - size, placement, alignment, color, useContainers - size, placement, alignment, color, use

And more…And more…

Single CSS to many Web PagesSingle CSS to many Web Pages

Many CSS to Single Web Page Many CSS to Single Web Page

CSS CSS

Physical layout

HeadingsBody

DevicesDevices

CSSCSS

CSSContent

Content

PRINTMOBILE

BROWSER

Different CSS for Different Type of Browser

The Box ModelThe Box Model

ExampleExample

Understanding BoxesUnderstanding Boxes

Parents and ChildrenParents and Children

An object that contains another is the parent of the object it An object that contains another is the parent of the object it containscontainsAn object contained by another is the child of the object An object contained by another is the child of the object containing itcontaining it

Types of CSSTypes of CSS

ExternalExternal

EmbeddedEmbedded

ImportedImported

InlineInline

ExternalExternal

Connection made via the LINK tagConnection made via the LINK tag

Use the optional TYPE attribute to specify Use the optional TYPE attribute to specify a media typea media type– type/csstype/css

Internal/EmbeddedInternal/Embedded

Style characteristics are embedded in the Style characteristics are embedded in the HEAD section of the webpageHEAD section of the webpage

Perhaps best used when a single page Perhaps best used when a single page requires a unique style sheetrequires a unique style sheet

ImportedImported

Allows for using style sheets from other Allows for using style sheets from other sourcessources

Must be included at the beginning of the Must be included at the beginning of the style sheet using the style sheet using the @import@import statement statement

Other CSS rules can be includedOther CSS rules can be included

InlineInline

Least flexibleLeast flexible

Requires each element to be tagged if you Requires each element to be tagged if you want them to appear differentlywant them to appear differently

Looses the advantage of using CSSLooses the advantage of using CSS

Inserting a CSSInserting a CSS

External sheetExternal sheet

</head></head>

Internal/embedded sheetInternal/embedded sheet

<head><head><style type=“text/css”><style type=“text/css”>hr { color: navy}hr { color: navy}body {margin-left: 20px}body {margin-left: 20px}</style></style></head></head>

Internal/embedded sheet for older browsersInternal/embedded sheet for older browsers

<!--<!-- hr { color: navy} hr { color: navy}

body {margin-left: 20px} body {margin-left: 20px} -->-->

</style></style>

</head></head>

InlineInline

This is a paragraphThis is a paragraph

</p></p>

Using multiple sheetsUsing multiple sheets

You can use multiple sheets to define the You can use multiple sheets to define the style of your documentstyle of your document

Internal styles will override external styles, Internal styles will override external styles, if they are duplicatedif they are duplicated

h3 {color: red; text-align: right; font-size: 8pt} h3 {color: red; text-align: right; font-size: 8pt} (external CSS)(external CSS)

h3 {text-align: center; font-size: 20pt} h3 {text-align: center; font-size: 20pt} (internal (internal CSS)CSS)

will yieldwill yield

h3 {h3 {color: redcolor: red; text-align: right; font-size: 8pt} ; text-align: right; font-size: 8pt} (external CSS)(external CSS)

h3 {h3 {text-align: centertext-align: center; ; font-size: 20ptfont-size: 20pt} } (internal (internal CSS)CSS)

will yieldwill yield

h3 {color: red; text-align: center; font-size: h3 {color: red; text-align: center; font-size: 20pt }20pt }

Sheet weight or PrecedenceSheet weight or Precedence

Author’s style sheet

User’s style sheet

Browser’s style sheet

Greatest weight Least weight

Sheet weight or PrecedenceSheet weight or Precedence

Understanding the CascadeUnderstanding the Cascade

CascadingCascading– Determining rule weight by specificityDetermining rule weight by specificity

Rules with more specific selectors take precedence over Rules with more specific selectors take precedence over rules with less specific selectorsrules with less specific selectors

– Determining rule weight by orderDetermining rule weight by orderBased on order of rule within style sheetBased on order of rule within style sheet

– Those listed later take precedence over those listed earlier in Those listed later take precedence over those listed earlier in the style sheetthe style sheet

Understanding the CascadeUnderstanding the Cascade

InheritanceInheritance– Based on hierarchical structure of documentsBased on hierarchical structure of documents

CSS rules inherit from parent elements to child CSS rules inherit from parent elements to child elements:elements:

– thus <LI> elements will inherit style rules from <UL> thus <LI> elements will inherit style rules from <UL> elements unless a style rule is specifically set for the elements unless a style rule is specifically set for the <LI> element<LI> element

Basic CSS SyntaxBasic CSS Syntax

Three parts:Three parts:– selectorselector– propertyproperty– valuevalue

selector {property: value}selector {property: value}

} declaration

selectorselector: the basic HTML element tag you wish : the basic HTML element tag you wish to define to define

bodybody

propertyproperty: the attribute of the selector that you : the attribute of the selector that you wish to changewish to change

bodybody {color {color

valuevalue: the particular markup value for that : the particular markup value for that attributeattribute

bodybody {color{color : black} : black}

If the If the valuevalue has multiple words, put the value in has multiple words, put the value in quotesquotes

p {font-family: p {font-family: “sans serif”“sans serif” } }

You can specify multiple You can specify multiple propertiesproperties to a single to a single selector. Properties must be separated by a selector. Properties must be separated by a semicolon.semicolon.

P { text-align: leftP { text-align: left;; color: red } color: red }

To make properties more readable, put each on To make properties more readable, put each on a separate line.a separate line.

p { text-align: center;p { text-align: center;

color: navy;color: navy;

font-family: arialfont-family: arial

SelectorsSelectors can be grouped so that a common can be grouped so that a common property can be specifiedproperty can be specified

h1,h2,h3,h4,h5,h6h1,h2,h3,h4,h5,h6

{ color: yellow }{ color: yellow }

<h1> <h1> This is a level 1 headingThis is a level 1 heading </h1> </h1>

<h2> <h2> This is a level 2 headingThis is a level 2 heading </h2> </h2>

SelectorsSelectors can be descendants can be descendants

P B P B { color: yellow }{ color: yellow }

In this example, only those In this example, only those <B><B> elements within a elements within a <P><P> element would be yellowelement would be yellow

<p><b> <p><b> This would be yellow This would be yellow </b></p></b></p>

<p> This would not be yellow<p> This would not be yellow </p></p>

CSS Syntax - classCSS Syntax - class

The The classclass selector allows you to create different selector allows you to create different styles for the same HTML element.styles for the same HTML element.

p.right { text-align: right }p.right { text-align: right }

p.center { text-align: center }p.center { text-align: center }

p.right { text-align: right }p.right { text-align: right }

<p <p classclass=“right”>=“right”>

This paragraph will be right aligned.This paragraph will be right aligned.

</p></p>

Note: the class name must be in quotes inside Note: the class name must be in quotes inside the opening tagthe opening tag

This is improper use of the class This is improper use of the class selectorselector::

<p <p classclass=“right” =“right” classclass=“center”>=“center”>This paragraph will be right aligned.This paragraph will be right aligned.

</p></p>

Only one class selector can be included inside Only one class selector can be included inside the tagthe tag

You can also create a class selector free of a You can also create a class selector free of a tag name if you want all tags that have that tag name if you want all tags that have that class to be formatted the same.class to be formatted the same.

.center { text-align: center }.center { text-align: center }

Any tag with a “center” class will be aligned Any tag with a “center” class will be aligned centercenter

..centercenter { text-align: center } { text-align: center }

<h1 <h1 classclass=“center”>=“center”>

This heading will be centeredThis heading will be centered

</h1></h1>

<p <p classclass=“center”>=“center”>

So will this textSo will this text

</p></p>

CSS Syntax - idCSS Syntax - id

While the class selector can apply to several While the class selector can apply to several different elements, the different elements, the idid selector can only selector can only apply to one, unique element.apply to one, unique element.

pp##para1 { text-align: center;para1 { text-align: center;

color: green }color: green }

CSS Syntax - idCSS Syntax - id

pp##para1 { text-align: center;para1 { text-align: center;

color: green }color: green }

This text would be centered and greenThis text would be centered and green

</p></p>

CSS syntax - <div>CSS syntax - <div>

<DIV> can be used with the CLASS attribute to <DIV> can be used with the CLASS attribute to create customized block-level elementscreate customized block-level elements– Declare it in the style rule:Declare it in the style rule:

DIV.introduction {font-size: 14pt; margin: 24 pt;}DIV.introduction {font-size: 14pt; margin: 24 pt;}

– Apply the style rule in the document:Apply the style rule in the document:<DIV CLASS=“introduction””>This is the introduction to the <DIV CLASS=“introduction””>This is the introduction to the document</DIV>document</DIV>

CSS syntax - <span>CSS syntax - <span>

<SPAN> can be used with the CLASS attribute <SPAN> can be used with the CLASS attribute to create customized inline elementsto create customized inline elements– Declare it in the style rule:Declare it in the style rule:

SPAN.logo {color: white; background-color: black;}SPAN.logo {color: white; background-color: black;}

– Apply the style rule in the document:Apply the style rule in the document:<P>Welcome to the <SPAN CLASS=“logo””> Wonder <P>Welcome to the <SPAN CLASS=“logo””> Wonder Software</SPAN>Web site</P>Software</SPAN>Web site</P>

Background PropertiesBackground Properties

Background propertiesBackground properties

Define the background effects of an Define the background effects of an elementelement

Effects include color, using an image for a Effects include color, using an image for a background, repeating an image and background, repeating an image and positioning an imagepositioning an image

Basic syntaxBasic syntax– backgroundbackground– background-colorbackground-color– background-imagebackground-image– background-repeatbackground-repeat– background-attachmentbackground-attachment– background-positionbackground-position

All attributes can be set in a single All attributes can be set in a single declaration:declaration:

background: #000000 url(‘mark.gif’) no-background: #000000 url(‘mark.gif’) no-repeat fixed centerrepeat fixed center

Setting the body background (internal Setting the body background (internal CSS)CSS)

body { background: #000000 url(‘mark.gif’) body { background: #000000 url(‘mark.gif’) no-repeat fixed center }no-repeat fixed center }

Setting the body background (external Setting the body background (external CSS)CSS)

body: { background: #000000 url(‘mark.gif’) body: { background: #000000 url(‘mark.gif’) no-repeat fixed center }no-repeat fixed center }

Elements can also be set separatelyElements can also be set separately

bodybody

{ { background-imagebackground-image: url(mark.gif);: url(mark.gif);

background-colorbackground-color: navy }: navy }

Text PropertiesText Properties

Text propertiesText properties

Controls the appearance of text in the web Controls the appearance of text in the web pagepage

Commonly used attributesCommonly used attributes– colorcolor– directiondirection– text-aligntext-align– text-decorationtext-decoration– text-indenttext-indent

colorcolor– sets the color of the textsets the color of the text– color can be represented by the color color can be represented by the color namename

(red), an (red), an rgbrgb value (rgb(255,0,0)), or by a value (rgb(255,0,0)), or by a hexadecimalhexadecimal number (#ff0000) number (#ff0000)

SyntaxSyntax– body {body {colorcolor: #ff0000}: #ff0000}

directiondirection– sets the direction of the textsets the direction of the text– can be set as left to right (can be set as left to right (ltrltr) or right to left ) or right to left

((rtlrtl))

SyntaxSyntax– body {body {directiondirection: rtl}: rtl}

text-aligntext-align– aligns the text in an elementaligns the text in an element– possible values are possible values are leftleft, , rightright, , centercenter and and

justifyjustify

SyntaxSyntax– p {p {text-aligntext-align: center}: center}

text-decorationtext-decoration– adds certain decoration elements to the textadds certain decoration elements to the text– possible values are possible values are nonenone, , underlineunderline, , overlineoverline, ,

line-throughline-through and and blinkblink

SyntaxSyntax– p {p {text-decorationtext-decoration: underline}: underline}

text-indenttext-indent– indents the first line of text inside an elementindents the first line of text inside an element– possible values are possible values are lengthlength (defines a fixed (defines a fixed

value) and value) and %% (defines a % of the parent (defines a % of the parent element)element)

SyntaxSyntax– p {p {text-indenttext-indent: 20px}: 20px}

Font PropertiesFont Properties

Font propertiesFont properties

Define the look of the font in text areasDefine the look of the font in text areas

One of the broader sets of properties in One of the broader sets of properties in CSSCSS

fontfont font-stylefont-style

font-variantfont-variant

font-weightfont-weight

font-size/line-heightfont-size/line-height

font-familyfont-family

font-stylefont-style normalnormal

italicitalic

obliqueoblique

Syntax: body {font-style: italic}

font-variantfont-variant normalnormal– font displays as isfont displays as is

small-capssmall-caps– font displays in all font displays in all

capitals, with lower case capitals, with lower case letters in smaller sizeletters in smaller size

Syntax: body {font-variant: small-caps}

font-weightfont-weight normalnormal

boldbold

bolderbolder

lighterlighter

weighted valuesweighted values

Syntax: body {font-weight: bold}

Weighted valuesWeighted values

range from 100 – 900range from 100 – 900

400 is the same as normal weight400 is the same as normal weight

700 is the same as bold weight700 is the same as bold weight

font-sizefont-size xx-small to xx-largexx-small to xx-large

smallersmaller– smaller than parentsmaller than parent

largerlarger– larger than parentlarger than parent

%%– % of the parent% of the parent

Syntax: body {font-size: 20px} {font-size: x-large} {font-size: 125%}

font-familyfont-family family-namefamily-name– “ “times”, “arial”, “courier”, times”, “arial”, “courier”,

“verdana”“verdana”

generic-familygeneric-family– ““serif”, “sans-serif”, serif”, “sans-serif”,

“monospace”“monospace”

Syntax: body {font-family: verdana, sans-serif}

Border PropertiesBorder Properties

Border propertiesBorder properties

Allows you to specify the style, color and Allows you to specify the style, color and width of an element’s borderwidth of an element’s border

Many different properties can be appliedMany different properties can be applied

Border propertiesBorder properties

You can specify the width, style, color, thickness You can specify the width, style, color, thickness and on which sides the border appearsand on which sides the border appears

Margin PropertiesMargin Properties

Margin propertiesMargin properties

Define the space around elementsDefine the space around elementsYou can use negative values to overlap You can use negative values to overlap contentcontentMargins can be set independently or Margins can be set independently or collectivelycollectivelyCan be set to auto, a fixed length or a % of Can be set to auto, a fixed length or a % of the total height of the documentthe total height of the document

PropertiesProperties– marginmargin– margin-topmargin-top– margin-rightmargin-right– margin-bottommargin-bottom– margin-leftmargin-left

margin-bottommargin-bottom autoauto– set by the browserset by the browser

lengthlength– fixedfixed

Syntax: h1 {margin-bottom: 20px}

Can be set in one declarationCan be set in one declaration

Think clock faceThink clock face– toptop, , rightright, , bottombottom, left, left

h1 {margin: 10px 20px 30px 40px}

All margins can be set the sameAll margins can be set the same

h1 {margin: 40px}

Margin settings can be paired (left and Margin settings can be paired (left and right, top and bottom)right, top and bottom)

h1 {margin: 40px 5%}

In this example, the top and bottom margins would be 40 pixels,While the left and right margins would be 5% of the total height of

the document.

0 size margins do not need to be 0 size margins do not need to be specified. 0px, 0pt and 0 are all equivalent.specified. 0px, 0pt and 0 are all equivalent.

h1 {margin: 40px 0 5% 0}

In this example, the top margin would be 40 pixels, the left andright margins would be 0, and the bottom margin would

be 5% of the total height of the document.

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