Shorthand properties
Shorthand properties are CSS properties that let you set the values of multiple other CSS properties in one declaration. Using a shorthand property, you can write more concise (and often more readable) style sheets, saving time and energy.
The CSS specification defines shorthand properties to group the definition of common properties acting on the same theme. For example, the CSS background property is a shorthand property that's able to define the values of background-color, background-image, background-repeat, and background-position.
Tricky edge cases
There are a few edge cases to keep in mind when using shorthand properties.
Omitting properties
A value which is not specified is set to a default value defined by the shorthand, which may differ from the property's initial value.
That means that it overrides previously set values. For example:
p {
background-color: red;
background: url("images/bg.gif") no-repeat left top;
}
This will not set the color of the background to red but to the default value for background-color, which is transparent.
Only the individual properties values can inherit. As missing values are replaced by their initial value, it is impossible to allow inheritance of individual properties by omitting them. The keyword inherit can be applied to a property, but only as a whole, not as a keyword for one value or another. That means that the only way to make some specific value to be inherited is to use the longhand property with the keyword inherit.
Ordering properties
Shorthand properties try not to force a specific order for the values of the properties they replace. This works well when these properties use values of different types, as the order has no importance, but this does not work as easily when several properties can have identical values.
Two important cases here are:
Sides of the box
Shorthands handling properties related to the sides of the box, like border-style, margin or padding, always use a consistent 1-to-4-value syntax representing those sides:
1-value syntax: border-width: 1em — A single value represents all sides: 
2-value syntax: border-width: 1em 2em — The first value represents the top and bottom sides, and the second value represents the left and right sides: 
3-value syntax: border-width: 1em 2em 3em — The first value represents the top side, the second value represents the left and right sides, and the third value represents the bottom side: 
4-value syntax: border-width: 1em 2em 3em 4em — The four values represent the top, the right, the bottom, and the left sides, respectively, always in that order; that is, clock-wise starting at the top: 
The initial letter of Top-Right-Bottom-Left matches the order of the consonant of the word trouble: TRBL. You can also remember it as the order that the hands would rotate on a clock: 1em starts in the 12 o'clock position, then 2em in the 3 o'clock position, then 3em in the 6 o'clock position, and 4em in the 9 o'clock position.
Corners of the box
Similarly, shorthands handling properties related to the corners of the box, like border-radius, always use a consistent 1-to-4-value syntax representing those corners:
1-value syntax: border-radius: 1em — A single value represents all corners: 
2-value syntax: border-radius: 1em 2em — The first value represents the top-left and bottom-right corners, and the second value represents the top-right and bottom-left corners: 
3-value syntax: border-radius: 1em 2em 3em — The first value represents the top-left corner, the second value represents the top-right and bottom-left corners, and the third value represents the bottom-right corner: 
4-value syntax: border-radius: 1em 2em 3em 4em — The four values represent the top-left, top-right, bottom-right, and bottom-left corners respectively, always in that order; that is, clock-wise starting at the top-left: 
Background properties
Consider a background with the following properties
background-color: black;
background-image: url("images/bg.gif");
background-repeat: no-repeat;
background-position: left top;
These four declarations can be shortened to just one:
background: black url("images/bg.gif") no-repeat left top;
(The shorthand form is actually the equivalent of the longhand properties above plus background-attachment: scroll and, in CSS3, some additional properties.)
See background for more detailed information, including CSS3 properties.
Font properties
Consider the following declarations:
font-style: italic;
font-weight: bold;
font-size: 0.8em;
line-height: 1.2;
font-family: "Arial", sans-serif;
These 5 statements can be shortened to the following:
font:
italic bold 0.8em/1.2 "Arial",
sans-serif;
This shorthand declaration is actually equivalent to the longhand declarations above plus font-variant: normal, font-size-adjust: none, and font-stretch: normal.
Border properties
With borders, the width, color, and style can be simplified into one declaration. For example, consider the following CSS:
border-width: 1px;
border-style: solid;
border-color: black;
It can be simplified as:
Margin and padding properties
Shorthand versions of margin and padding values work similarly; the margin property allows for shorthand values to be specified using one, two, three, or four values. Consider the following CSS declarations:
margin-top: 10px;
margin-right: 5px;
margin-bottom: 10px;
margin-left: 5px;
They are the same as the following declaration using the four value shorthand. Note that the values are in clockwise order, beginning at the top: top, right, bottom, then left (TRBL, the consonants in "trouble").
margin: 10px 5px 10px 5px;
Margin shorthand rules for one, two, three and four value declarations are:
- When one value is specified, it applies the same margin to all four sides.
- When two values are specified, the first margin applies to the top and bottom, the second to the left and right.
- When three values are specified, the first margin applies to the top, the second to the left and right, the third to the bottom.
- When four values are specified, the margins apply to the top, right, bottom, and left in that order (clockwise).
Position properties
With position, the shorthand versions of top, right, bottom and left can be simplified into one declaration. For example, consider the following CSS:
top: 0;
right: 20px;
bottom: 0;
left: 20px;
It can be simplified as:
Just like margins and paddings, the inset values are ordered clockwise - top, right, bottom, then left (TRBL).
The universal shorthand property
CSS provides a universal shorthand property, all, which applies its value to every property in the document. Its purpose is to change the properties' inheritance model.
See Handling conflicts or Introducing the CSS Cascade for more information about how inheritance works in CSS.
Shorthand properties
See also