Web Programming Step by Step

Chapter 3
CSS for Styling

3.1: Basic CSS

3.1: Basic CSS
3.2: More CSS

The bad way to produce styles

<p>
	<font face="Arial">Welcome to Greasy Joe's.</font>
	You will <b>never</b>, <i>ever</i>, <u>EVER</u> beat 
	<font size="+4" color="red">OUR</font> prices!
</p>

tags such as b, i, u, and font are discouraged in strict XHTML
- Why is this bad?

Cascading Style Sheets (CSS)

describe the appearance, layout, and presentation of information on a web page
- (as opposed to HTML, which describes the content of the page)
describe how information is to be displayed, not what is being displayed
can be embedded in HTML document or placed into separate .css file
- with a .css file, one style sheet can be shared across many pages

Basic CSS rule syntax (3.1.1)

selector {
	property: value;
	property: value;
	...
	property: value;
}

p {
  font-family: sans-serif;
  color: red;
}

a CSS file consists of one or more rules
each rule starts with a selector that specifies an HTML element(s) and then applies style properties to them
- a selector of * selects all elements

Attaching a CSS file: `<link>` (3.1.2)

<head>
	...
	<link href="filename" type="text/css" rel="stylesheet" />
	...
</head>

<link href="style.css" type="text/css" rel="stylesheet" />

<link href="http://www.google.com/uds/css/gsearch.css"
	rel="stylesheet" type="text/css" />

a page can link to multiple style sheet files
- in case of a conflict (two sheets define a style for the same HTML element), the latter sheet's properties will be used

Aside: Favorites icon ("favicon")

<link href="filename" type="MIME type" rel="shortcut icon" />

<link href="yahoo.gif" type="image/gif" rel="shortcut icon" />

the link tag, placed in the HTML page's head section, can specify an icon for a web page
- this icon will be placed in the browser title bar and bookmark/favorite
IE6: this doesn't work; must place a file in .ico format named favicon.ico in the root directory of the web server (instructions)

Embedding style sheets: `<style>`

<head>
	<style type="text/css">
		p { font-family: sans-serif; color: red; }
		h2 { background-color: yellow; }
	</style>
</head>

CSS code can be embedded within the head of an HTML page
this is bad style and should be avoided when possible (why?)

Inline styles: the `style` attribute

<p style="font-family: sans-serif; color: red;">
This is a paragraph</p>

higher precedence than embedded or linked styles
used for one-time overrides and styling a particular element
this is bad style and should be avoided when possible (why?)

CSS properties for colors (3.1.3)

p {
	color: red;
	background-color: yellow;
}

This paragraph uses the style above.

property	description
`color`	color of the element's text
`background-color`	color that will appear behind the element

Specifying colors

p { color: red; }
h2 { color: rgb(128, 0, 196); }
h4 { color: #FF8800; }

This paragraph uses the first style above.

This h2 uses the second style above.

This h4 uses the third style above.

color names: aqua, black, blue, fuchsia, gray, green, lime, maroon, navy, olive, purple, red, silver, teal, white (white), yellow
RGB codes: red, green, and blue values from 0 (none) to 255 (full)
hex codes: RGB values in base-16 from 00 (0, none) to FF (255, full)

Grouping styles

p, h1, h2 {
	color: green;
}
h2 {
	background-color: yellow;
}

This paragraph uses the above style.

This h2 uses the above styles.

a style can select multiple elements separated by commas
the individual elements can also have their own styles (like h2 above)

CSS comments: `/` ... `/` (3.1.4)

/* This is a comment.
  It can span many lines in the CSS file. */
p {
	color: red; background-color: aqua;
}

CSS (like HTML) is usually not commented as rigorously as programming languages such as Java
the // single-line comment style is NOT supported in CSS
the  HTML comment style is also NOT supported in CSS

CSS properties for fonts (3.1.5)

property	description
`font-family`	which font will be used
`font-size`	how large the letters will be drawn
`font-style`	used to enable/disable italic style
`font-weight`	used to enable/disable bold style
Complete list of font properties

`font-family`

p {
	font-family: Georgia;
}
h2 {
	font-family: "Courier New";
}

This paragraph uses the first style above.

This h2 uses the second style above.

enclose multi-word font names in quotes

More about `font-family`

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

This paragraph uses the above style.

can specify multiple fonts from highest to lowest priority
generic font names:
serif, sans-serif, cursive, fantasy, monospace

if the first font is not found on the user's computer, the next is tried
generally should specify similar fonts
placing a generic font name at the end of your font-family value ensures that every computer will use a valid font

`font-size`

p {
	font-size: 14pt;
}

This paragraph uses the style above.

units: pixels (px) vs. point (pt) vs. m-size (em)
16px, 16pt, 1.16em
vague font sizes: xx-small, x-small, small, medium, large, x-large, xx-large, smaller, larger
percentage font sizes, e.g.: 90%, 120%

pt specifies number of point, where a point is 1/72 of an inch onscreen
px specifies a number of pixels on the screen
em specifies number of m-widths, where 1 em is equal to the font's current size

`font-weight`, `font-style`

p {
	font-weight: bold;
	font-style: italic;
}

This paragraph uses the style above.

either of the above can be set to normal to turn them off (e.g. headings)

Spying on styles with Firebug

firebug firebug

install Firebug Firefox add-on to inspect XHTML/CSS of any page
can see what styles apply to which elements, and change them dynamically

Why `<strong>`, `<em>` and not `<b>`, `<i>`?

strong { font-weight: normal; color: red; }
em { font-style: normal; background-color: #DDDDDD; }

Now if I want to strongly emphasize something or just emphasize it, it doesn't necessarily have to be bold or italic.

strong and em describe attributes of the content ("This is something important in the document.")
b and i describe formatting and presentation ("I want this to be bold.")

CSS properties for text (3.1.6)

property	description
`text-align`	alignment of text within its element
`text-decoration`	decorations such as underlining
`line-height`, `word-spacing`, `letter-spacing`	gaps between the various portions of the text
`text-indent`	indents the first letter of each paragraph
Complete list of text properties

`text-align`

blockquote { text-align: justify; }
h2 { text-align: center; }

The Emperor's Quote

[TO LUKE SKYWALKER] The alliance... will die. As will your friends. Good, I can feel your anger. I am unarmed. Take your weapon. Strike me down with all of your hatred and your journey towards the dark side will be complete.

text-align can be left, right, center, or justify (which widens all full lines of the element so that they occupy its entire width)

`text-decoration`

p {
	text-decoration: underline;
}

This paragraph uses the style above.

can also be overline, line-through, blink, or none
effects can be combined:
text-decoration: overline underline;

The `list-style-type` property (3.2.4)

ol { list-style-type: lower-roman; }

Possible values:
1. none : No marker
2. disc (default), circle, square
3. decimal : 1, 2, 3, etc.
4. decimal-leading-zero : 01, 02, 03, etc.
5. lower-roman : i, ii, iii, iv, v, etc.
6. upper-roman : I, II, III, IV, V, etc.
7. lower-alpha : a, b, c, d, e, etc.
8. upper-alpha : A, B, C, D, E, etc.
9. lower-greek : alpha, beta, gamma, etc.
10. others: hebrew, armenian, georgian, cjk-ideographic, hiragana, katakana, hiragana-iroha, katakana-iroha

3.2: More CSS

3.1: Basic CSS
3.2: More CSS

Body styles

body {
	font-size: 16px;
}

to apply a style to the entire body of your page, write a selector for the body element
saves you from manually applying a style to each element

Cascading style sheets

it's called Cascading Style Sheets because the properties of an element cascade together in this order:
- browser's default styles
- external style sheet files (in a <link> tag)
- internal style sheets (inside a <style> tag in the page's header)
- inline style (the style attribute of the HTML element)

Inheriting styles (explanation) (3.2.1)

body { font-family: sans-serif; background-color: yellow; }
p { color: red; background-color: aqua; }
a { text-decoration: overline underline; }
h2 { font-weight: bold; text-align: center; }

This is a heading.

A styled paragraph. Previous slides are available on the web site.

a bulleted list

when multiple styles apply to an element, they are inherited
a more tightly matching rule can override a more general inherited rule
not all properties are inherited (notice link's color above)

Styles that conflict

p, h1, h2 { color: blue; font-style: italic; }
h2 { color: red; background-color: yellow; }

This paragraph uses the first style above.

This heading uses both styles above.

when two styles set conflicting values for the same property, the latter style takes precedence

The HTML `id` attribute (3.2.2)

<p>Spatula City!  Spatula City!</p>
<p id="mission">Our mission is to provide the most
spectacular spatulas and splurge on our specials until our
customers <q>esplode</q> with splendor!</p>

allows you to give a unique ID to any element on a page
each ID must be unique; can only be used once in the page

Linking to sections of a web page

<p>Visit <a href=
		"http://www.textpad.com/download/index.html#downloads">
	textpad.com</a> to get the TextPad editor.</p>

<p><a href="#mission">View our Mission Statement</a></p>

a link target can include an ID at the end, preceded by a #
browser will load that page and scroll to element with given ID

CSS ID selectors

#mission {
	font-style: italic;
	font-family: "Garamond", "Century Gothic", serif;
}

Spatula City! Spatula City!

Our mission is to provide the most spectacular spatulas and splurge on our specials until our customers esplode with splendor!

applies style only to the paragraph that has the ID of mission
element can be specified explicitly: p#mission {

The HTML `class` attribute (3.2.3)

<p class="standout">Spatula City!  Spatula City!</p>
<p class="special">See our spectacular spatula specials!</p>
<p class="special">Today only: satisfaction guaranteed.</p>

classes are a way to group some elements and give a style to only that group
(I don't want ALL paragraphs to be yellow, just these three...)
unlike an id, a class can be reused as much as you like on the page

CSS class selectors

.special {
	background-color: yellow;
	font-weight: bold;
}
p.standout {
	color: red;
	font-family: cursive;
}

Spatula City! Spatula City!

See our spectacular spatula specials!

Today only: satisfaction guaranteed.

applies rule to any element with class special or a p with class standout

Multiple classes

<h2 class="standout">Spatula City!  Spatula City!</h2>
<p class="special">See our spectacular spatula specials!</p>
<p class="special standout">Satisfaction guaranteed.</p>
<p class="standout">We'll beat any advertised price!</p>

Spatula City! Spatula City!

See our spectacular spatula specials!

Satisfaction guaranteed.

We'll beat any advertised price!

an element can be a member of multiple classes (separated by spaces)

CSS pseudo-classes

a:link    { color: #FF0000; }      /* unvisited link */
a:visited { color: #00FF00; }      /* visited link */
a:hover   { color: #FF00FF; }      /* mouse over link */

Buy early, buy often!

class	description
`:active`	an activated or selected element
`:focus`	an element that has the keyboard focus
`:hover`	an element that has the mouse over it
`:link`	a link that has not been visited
`:visited`	a link that has already been visited
`:first-letter`	the first letter of text inside an element
`:first-line`	the first line of text inside an element
`:first-child`	an element that is the first one to appear inside another

CSS properties for backgrounds

property	description
`background-color`	color to fill background
`background-image`	image to place in background
`background-position`	placement of bg image within element
`background-repeat`	whether/how bg image should be repeated
`background-attachment`	whether bg image scrolls with page
`background`	shorthand to set all background properties

`background-image`

body {
	background-image: url("images/draft.jpg");
}

This is the first paragraph

This is the second paragraph...
It occupies 2 lines

background image/color fills the element's content area

`background-repeat`

body {
	background-image: url("images/draft.jpg");
	background-repeat: repeat-x;
}

This is the first paragraph

This is the second paragraph...
It occupies 2 lines

can be repeat (default), repeat-x, repeat-y, or no-repeat

`background-position`

body {
	background-image: url("images/draft.jpg");
	background-repeat: no-repeat;
	background-position: 370px 20px;
}

This is the first paragraph

This is the second paragraph...
It occupies 2 lines

value consists of two tokens, each of which can be top, left, right, bottom, center, a percentage, or a length value in px, pt, etc.
value can be negative to shift left/up by a given amount

Showing a partial image

.partialimage1, .partialimage2 {
	background-image: url("images/sex_and_the_city.jpg");
	background-repeat: no-repeat;
	width: 70px;   height: 200px;
}
.partialimage1 { background-position: 0px 0px; }
.partialimage2 { background-position: -115px 0px; }

W3C CSS Validator (3.2.6)

<p>
	<a href="http://jigsaw.w3.org/css-validator/check/referer">
		<img src="http://jigsaw.w3.org/css-validator/images/vcss"
			alt="Valid CSS!" /></a>
</p>

jigsaw.w3.org/css-validator/
checks your CSS to make sure it meets the official CSS specifications
more picky than the web browser, which may render malformed CSS correctly

Web Programming Step by Step, Chapter 3

CSS for Styling

Chapter 3 CSS for Styling

3.1: Basic CSS

The bad way to produce styles

Cascading Style Sheets (CSS)

Basic CSS rule syntax (3.1.1)

Attaching a CSS file: <link> (3.1.2)

Aside: Favorites icon ("favicon")

Embedding style sheets: <style>

Inline styles: the style attribute

CSS properties for colors (3.1.3)

Specifying colors

This h2 uses the second style above.

This h4 uses the third style above.

Grouping styles

This h2 uses the above styles.

CSS comments: /* ... */ (3.1.4)

CSS properties for fonts (3.1.5)

This h2 uses the second style above.

More about font-family

font-weight, font-style

Spying on styles with Firebug

Why <strong>, <em> and not <b>, <i>?

CSS properties for text (3.1.6)

The Emperor's Quote

The list-style-type property (3.2.4)

3.2: More CSS

Body styles

Cascading style sheets

Inheriting styles (explanation) (3.2.1)

This is a heading.

Styles that conflict

This heading uses both styles above.

The HTML id attribute (3.2.2)

Linking to sections of a web page

CSS ID selectors

The HTML class attribute (3.2.3)

CSS class selectors

Multiple classes

Spatula City! Spatula City!

CSS pseudo-classes

CSS properties for backgrounds

Showing a partial image

W3C CSS Validator (3.2.6)

Chapter 3
CSS for Styling

Attaching a CSS file: `<link>` (3.1.2)

Embedding style sheets: `<style>`

Inline styles: the `style` attribute

CSS comments: `/` ... `/` (3.1.4)

More about `font-family`

`font-weight`, `font-style`

Why `<strong>`, `<em>` and not `<b>`, `<i>`?

The `list-style-type` property (3.2.4)

The HTML `id` attribute (3.2.2)

The HTML `class` attribute (3.2.3)