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- Appendix C: CSS Properties
Value IE N FF Inherited No
auto 7 - 1 Default auto
[length] 7 - 1 Applies to Block elements
[percentage] 7 - 1
inherit - 6 1
min-height
This specifies the maximum height of a block-level element (same values as for height).
td {min-height:100px;}
Value IE N FF Inherited No
auto 7 - 1 Default auto
[length] 7 - 1 Applies to Block-level elements
[percentage] 7 - 1
inherit - 6 1
min-width
This specifies the minimum width of a block-level element (same values as for width).
td {min-width:200px;}
Value IE N FF Inherited No
auto 7 - 1 Default auto
[length] 7 - 1 Applies to Block elements
[percentage] 7 - 1
inherit - 6 1
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- Appendix C: CSS Properties
Margin Proper ties
Margin properties allow you to specify a margin around a box and therefore create a gap between elements’
borders.
margin (margin-bottom, margin-left,
margin-top, margin-right)
This specifies the width of a margin around a box.
p {margin:15px;}
Value IE N FF Inherited No
auto 3 4 1 Default zero
[length] 3 4 1 Applies to All elements
[percentage — 3 4 1
relative to parent
element]
inherit - 6 1
Padding Proper ties
Padding properties set the distance between the border of an element and its content. They are impor-
tant for adding white space to documents (in particular table cells).
padding (padding-bottom, padding-left,
padding-right, padding-top)
This specifies the distance between an element’s border and its content.
td {padding:20px;}
Value IE N FF Inherited No
auto 4 4 1 Default zero
[length] 4 4 1 Applies to All elements
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- Appendix C: CSS Properties
Value IE N FF
[percentage — 4 4 1
relative to parent
element]
inherit - 6 1
List Proper ties
List properties affect the presentation of bulleted, numbered, and definition lists.
list-style
This is shorthand allowing you to specify list-style-position and list-style-type.
ul {list-style: inside disc}
Value IE N FF Inherited Yes
4 6 1 Default Depends on browser
4 4 1 Applies to List elements
4 6 1
inherit - 6 1
list-style-position
This specifies whether the marker should be placed inside each item of a list or to the left of them.
ul {list-style-position:inside;}
Value IE N FF Inherited Yes
inside 4 6 1 Default outside
outside 4 6 1 Applies to List elements
inherit - 6 1
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- Appendix C: CSS Properties
list-style-type
This indicates the type of bullet or numbering that a bullet should use.
ul {list-style-type:circle;}
Value IE N FF Inherited Yes
None 4 4 1 Default disc
disc (default) 4 4 1 Applies to List elements
Circle 4 4 1
square 4 4 1
decimal 4 4 1
decimal-leading- - - -
zero
lower-alpha 4 4 1
upper-alpha 4 4 1
lower-roman 4 4 1
upper-roman 4 4 1
Additional numbered list styles are available in CSS, but unfortunately they are not supported in IE7,
Netscape 7, or Firefox 2.
hebrew Traditional Hebrew numbering
georgian Traditional Georgian numbering (an, ban, gan, . . . , he, tan,
in, in-an, . . .)
armenian Traditional Armenian numbering
cjk-ideographic Plain ideographic numbers
hiragana (a, i, u, e, o, ka, ki, . . . )
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- Appendix C: CSS Properties
katakana (A, I, U, E, O, KA, KI, . . . )
hiragana-iroha (i, ro, ha, ni, ho, he, to, . . . )
katakana-iroha (I, RO, HA, NI, HO, HE, TO, . . . )
marker-offset
This specifies the space between a list item and its marker.
ol {marker-offset:2em;}
Value IE N FF Inherited No
[length] - 7 1 Default auto
auto - 7 1 Applies to Marker elements
inherit - 6 1
Positioning Proper ties
Positioning properties allow you to use CSS for positioning boxes on the page.
position
Specifies the positioning schema that should be used for an element. When an element is positioned, you
also need to use the box-offset properties covered next (top, left, bottom, and right). Note that you
should not use top and bottom or left and right together (if you do, top and left take priority).
❑ absolute can be fixed on the canvas in a specific position from its containing element (which is
another absolutely positioned element); it will also move when the user scrolls the page.
❑ static will fix it on the page in the same place and keep it there even when the user scrolls.
❑ relative will be placed offset in relation to its normal position.
❑ fixed will fix it on the background of the page and not move when the user scrolls.
p.article{position:absolute; top:10px; left:20px;
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- Appendix C: CSS Properties
Value IE N FF Inherited No
absolute 4 4 1 Default static
relative 4 4 1 Applies to All elements
static 4 4 1
fixed - 6 1
inherit - 6 1
Top
This sets the vertical position of an element from the top of the window or containing element.
Value IE N FF Inherited No
auto 4 6 1 Default auto
[length] 4 6 1 Applies to Positioned elements
[percentage - 4 6 1
relative to
parent’s height]
Inherit - 6 1
Left
This sets the horizontal position of an element from the left of the window or containing element.
Value IE N FF Inherited No
Auto 4 6 1 Default auto
[length] 4 6 1 Applies to Positioned elements
[percentage - 4 6 1
relative to
parent’s width]
inherit - 6 1
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- Appendix C: CSS Properties
bottom
This sets the vertical position of an element from the bottom of the window or containing element.
Value IE N FF Inherited No
auto 5 6 1 Default auto
[length] 5 6 1 Applies to Positioned elements
[percentage - 5 6 1
relative to
parent’s height]
inherit - 6 1
right
This sets the horizontal position of an element from the window or containing element.
Value IE N FF Inherited No
auto 5 6 1 Default auto
[length] 5 6 1 Applies to Positioned elements
[percentage - 5 6 1
relative to
parent’s width]
inherit - 6 1
vertical-align
This sets the vertical positioning of an inline element:
❑ baseline aligns element with base of parent.
❑ middle aligns midpoint of element with half the height of parent.
❑ sub makes element subscript.
❑ super makes element superscript.
❑ text-top aligns element with top of parent element’s font.
❑ text-bottom aligns element with the bottom of parent element’s font.
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- Appendix C: CSS Properties
❑ top aligns top of element with top of tallest element on current line.
❑ bottom aligns element with bottom of lowest element on the current line.
span.superscript {vertical-align:superscript;}
Value IE N N Inherited No
baseline 4 4 1 Default baseline
middle 4 4 1 Applies to Inline elements
sub 4 6 1
super 4 6 1
text-top 4 4 1
text-bottom 4 4 1
top 4 4 1
bottom 4 4 1
[percentage relative - 6 1
to line height]
[length] - - -
inherit 4 6 1
z-index
Controls which overlapping element appears to be on top; works for absolutely positioned elements
only. Positive and negative numbers are permitted.
p {position:absolute; top:10px; left:20px; z-index:3;}
Value IE N FF Inherited No
auto 4 - 1 Default Depends on position
of element in XHTML
[number] 4 4 1 source document
inherit - 6 1 Applies to Positioned elements
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- Appendix C: CSS Properties
clip
Controls which part of an element is visible. Parts outside the clip are not visible. If value is rect(), it
takes the following form:
❑ rect([top] [right] [bottom] [left])
rect(25 100 100 25)
Value IE N FF Inherited No
auto 4 - 1 Default auto
rect 4 6 1 Applies to Block elements
inherit - 6 1
overflow
This specifies how a container element will display content that is too large for its containing element.
p {width:200px; height:200px; overflow:scroll;}
Value IE N FF Inherited No
auto 4 6 1 Default visible
hidden 4 6 1 Applies to Block elements
visible 4 6 1
scroll 4 6 1
inherit - 6 6
overflow-x
Same as overflow, but only for the horizontal x-axis. First supported in IE5.
overflow-y
Same as overflow, but only for the vertical y-axis. First supported in IE5.
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- Appendix C: CSS Properties
Outline Proper ties
Outlines act like borders, but do not take up any space — they sit on top of the canvas.
Outline (outline-color, outline-style, outline-width)
Shortcut for the outline-color, outline-style, and outline-width properties:
outline {solid #ff0000 2px}
Note that outline-color, outline-style, and outline-width take the same values as border-
color, border-style, and border-width. They are not covered individually, because they are not
supported yet.
Value IE N FF Inherited No
outline-color - - 1.5 Default none
outline-style - - 1.5 Applies to All elements
outline-width - - 1.5
outline - - 1.5
Table Proper ties
Table properties allow you to affect the style of tables, rows, and cells.
border-collapse
This specifies the border model that the table should use (whether adjacent borders should be collapsed
into one value or kept separate).
table {border-collapse:separate;}
Value IE N FF Inherited Yes
collapse 5 7 1 Default collapse
separate 5 7 1 Applies to Table and
inline
inherit - 6 1 elements
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- Appendix C: CSS Properties
border-spacing
This specifies the distance between adjacent cells’ borders.
table {border-spacing:2px;}
Value IE N FF Inherited Yes
[length] - 6 1 Default 0
inherit - 6 1 Applies to Table and inline
elements
caption-side
This indicates which side of a table a caption should be placed on.
caption {caption-side:bottom;}
Value IE N FF Inherited Yes
top - 6 1 Default top
left - 6 1 Applies to
elements in
bottom - 6 1 elements
right - 6 1
inherit - 6 1
empty-cells
This specifies whether borders should be displayed if a cell is empty.
td, th {empty-cells:hide;}
Value IE N FF Inherited Yes
show 5 6 1 Default show
hide 5 6 1 Applies to Table cell elements
inherit - 6 1
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- Appendix C: CSS Properties
table-layout
Specifies how the browser should calculate the layout of a table; can affect the speed of rendering a large
or graphics-intensive table.
Value IE N FF Inherited No
auto 5 6 1 Default auto
fixed 5 6 1 Applies to Table and
inline
inherit - 6 6 elements
Classification Proper ties
Classification properties affect how the boxes in the box model are rendered.
clear
Forces elements, which would normally wrap around an aligned element, to be displayed below it.
Value indicates which side may not touch an aligned element.
p {clear:left;}
Value IE N FF Inherited No
none 4 4 1 Default none
both 4 4 1 Applies to All elements
left 4 4 1
right 4 4 1
inherit - 6 1
display
Specifies how an element is rendered, if at all. If set to none the element is not rendered and it does not
take up any space. Can force an inline element to be displayed as a block or vice versa.
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- Appendix C: CSS Properties
span.important {display:block;}
Value IE N FF Inherited Yes
none 4 4 1 Default inline
inline 5 4 1 Applies to All elements
block 5 4 1
list-item 5 4 1
inherit - 6 1
Other properties are either not supported or not required for XHTML.
While the default value of this property is inline, browsers tend to treat the element depending on its
inherent display type. Block-level elements, such as headings and paragraphs, get treated as if the
default were block, whereas inline elements such as , , or get treated as inline.
float
Subsequent elements should be wrapped to the left or right of the element, rather than below.
img.featuredeItem {float:left;}
Value IE N FF Inherited No
none 4 4 1 Default none
left 4 4 1 Applies to All elements
right 4 4 1
inherit - 6 1
visibility
Specifies whether an element should be displayed or hidden. Even if hidden, elements take up space on
page, but are transparent.
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- Appendix C: CSS Properties
Value IE N FF Inherited No
visible 4 - 1 Default inherit
show - 4 1 Applies to All elements
hidden 4 - 1
hide - 4 1
collapse - - 1
inherit 4 4 1
Internationalization Proper ties
Internationalization properties affect how text is rendered in different languages.
direction
Specifies the direction of text from left to right or right to left. This should be used in association with the
unicode-bidi property.
td.word{direction:rtl; unicode-bidi:bidi-override;}
Value IE N FF Inherited Yes
ltr 5 6 1 Default ltr
rtl 5 6 1 Applies to All elements
inherit 5 6 1
unicode-bidi
The unicode-bidi property allows you to override Unicode’s built-in directionality settings for languages.
td.word{unicode-bidi:bidi-override; direction:rtl; }
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- Appendix C: CSS Properties
Value IE N FF Inherited No
normal 5 - 2 Default normal
embed 5 - 2 Applies to All elements
bidi-override 5 - 2
inherit - 6 2
Lengths
Following are the unit measurement for lengths that can be used in CSS.
Absolute Lengths
Unit IE N FF
cm 3 4 1
in 3 4 1
mm 3 4 1
pc 3 4 1
pt 3 4 1
Relative Lengths
Unit IE N FF
em 4 4 1
ex 4 4 1
px 3 4 1
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- D
Color Names and Values
The first thing you need to learn about color is how to specify exactly the color you want; after all,
there are a lot of different reds, greens, and blues, and it is important you choose the right ones.
In XHTML there are two key ways of specifying a color:
❑ Hex codes: A six-digit code representing the amount of red, green, and blue that make up
the color, preceded by a pound or hash sign # (for example, #333333).
❑ Color names: A set of names that represent over 200 colors, such as red, lightslategray,
and fuchsia.
In CSS you can also use values to represent the red, green, and blue values that make up each
color.
Using Hex Codes to Specify Colors
When you start using hexadecimal codes (or hex codes for short), they can appear a little daunting.
The idea that colors are represented by a mix of numbers and letters might seem a little strange,
but what follows the # sign is actually the amount of red, green, and blue that make up the color.
The format for hex codes is:
# rrggbb
The table that follows provides some examples.
- Appendix D: Color Names and Values
Color Hexadecimal Code Color Hexadecimal Code
Black #000000 Green #008000
White #FFFFFF Blue #0000FF
Red #FF0000 Purple #800080
As you might already know, computer monitors work in a color space known as an RGB color space.
When a computer monitor is not switched on, the screen is black because it is not emitting any color. To
create the image you see onscreen, each of the pixels that make up the screen emits different amounts of
the colors red, green, and blue, just like a television screen.
It’s hardly surprising, therefore, that you specify colors in the amounts of red, green, and blue that are
required to make a given color. The values of red, green, and blue required to make a color are between
0 and 255, so when red, green, and blue all have a value of 0 you get black, whereas if each has a value
of 255 you get white.
You may have seen that some software represents colors using three sets of numbers between 0 and 255.
Figure D-1 shows the color window in Adobe Photoshop.
Figure D-1
The hexadecimal codes used on the web for color are a direct translation of these values between 0 and
255, except they use two characters, not three, to represent the numbers between 0 and 255. For example,
FF represents 255 and 00 represents 0.
The best way to really understand how hex codes work is to take a quick look at how computers store
information.
Understanding Hex Codes
You may have heard people say that computers store all their information in 0s and 1s, and while it may
sound hard to believe, it’s true! The smallest unit of information a computer stores in is known as a bit,
and a bit can have only one of two values:
❑ 0, which means off (or false)
❑ 1, which means on (or true)
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- Appendix D: Color Names and Values
These two values on their own will not store much information, yet if you combine 4 bits together, you can
get 16 different values. For example, using combinations of four 0s and 1s, you can represent the digits 0
through 9 (and still have values to spare):
0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111
0 1 2 3 4 5 6 7 8 9 - - - - - -
Four bits can be replaced by a single hexadecimal digit. There are 16 digits in hexadecimal numbers to
represent the 16 possible values of four 0s and 1s:
0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111
0 1 2 3 4 5 6 7 8 9 A B C D E F
0 is the smallest; F is the largest.
Still, computers need to work with more than 16 possible values, so they tend to store information in even
larger segments. A group of 8 bits is known as a byte. A byte can therefore be represented using just two
hexadecimal digits. For example:
Binary 0100 1111
Hexadecimal 4 F
This gives 256 possible combinations of 0s and 1s, plenty for the characters of the English language, and
yes, that is why colors are represented in numbers between 0 and 255.
So, while hexadecimal codes for web colors may appear a little complicated, I think you would agree
that #4F4F4F is a lot easier to read than 010011110100111101001111. The following table shows some
more hexadecimal codes and their corresponding decimal numbers.
Hexadecimal Decimal Hexadecimal Decimal
00 0 BB 187
33 51 CC 204
66 102 DD 221
99 153 EE 238
AA 170 FF 255
Using Color Names to Specify Colors
Rather than using hex values to specify colors, you can also use color names such as red, green, and
white to specify the color you want. There are more than 200 different color names supported by
Netscape, Firefox, and IE, all of which are listed at the end of this appendix.
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- Appendix D: Color Names and Values
Although names might sound a lot easier to understand than hex codes, some of the colors are easier to
remember than others, and remembering which color each of the 200 names looks like is a tall order.
Here is a sample of some of the color names:
aqua, beige, coral, darkcyan, firebrick, green, honeydew, indianred,
lavenderblush, maroon, navy, oldlace, palegreen, red, saddlebrown,
tan, white, yellow
Furthermore, if you do jobs for larger companies, such companies often want to specify very exact colors
that represent their brand, and their color might not have an HTML name. Indeed, when clients specify
the color they want, they usually specify a hex code.
Hex Codes versus Color Names
It may seem as though color names are more straightforward to use than hex codes; if you use colors such
as red, orange, green, blue, black, and white, then they are simple to remember and use. However, remem-
bering each color name and the color it gives you is very difficult.
In practice, you often end up referring to a color chart to find the color you want, whether you’re work-
ing with hex codes or color names. Given that hex codes give you many more choices of shades, tints, and
hues of colors than color names, and bearing in mind that a lot of companies ask for specific colors to
represent their company, hex codes tend to be the choice of web professionals.
If you are using either a graphics program or a web page authoring tool, that program will usually gen-
erate the color code you need for you, and many graphics packages also have a color-picking tool to help
you select the exact color you want. You can also find color picking tools on several web sites such as
www.visibone.com/colorlab/. Figure D-2 shows the color picker from Photoshop.
Figure D-2
Note that the checkbox on the bottom left of this window indicates an option to use only web-safe colors.
This is for a restricted color palette (containing a subset of all colors available) known as the Web Safe Color
Palette, which was designed in the days when computers did not support as many colors. Nowadays,
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