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Shorthand properties

Shorthand properties are CSS properties that let you set the values of multiple other CSS properties simultaneously. 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 instance, 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. Similarly, the most common font-related properties can be defined using the shorthand font, and the different margins around a box can be defined using the margin shorthand.

Tricky edge cases

Even if they are very convenient to use, there are a few edge cases to keep in mind when using them:

A value which is not specified is set to its initial value. That sounds anecdotal, but it really means that it overrides previously set values. Therefore:
```
background-color: red;
background: url(images/bg.gif) no-repeat left top;
```
will not set the color of the background to red but to background-color's default, transparent, as the second rule has precedence.
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.

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. Handling of these cases are grouped in several categories:

Shorthands handling properties related to edges of a box, like border-style, margin or padding, always use a consistent 1-to-4-value syntax representing those edges:

	The 1-value syntax: `border-width: 1em` — The unique value represents all edges
	The 2-value syntax: `border-width: 1em 2em` — The first value represents the vertical, that is top and bottom, edges, the second the horizontal ones, that is the left and right ones.
	The 3-value syntax: `border-width: 1em 2em 3em` — The first value represents the top edge, the second, the horizontal, that is left and right, ones, and the third value the bottom edge
	The 4-value syntax: `border-width: 1em 2em 3em 4em` — The four values represent the top, right, bottom and left edges 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)

Similarly, shorthands handling properties related to corners of a box, like border-radius, always use a consistent 1-to-4-value syntax representing those corners:

	The 1-value syntax: `border-radius: 1em` — The unique value represents all corners
	The 2-value syntax: `border-radius: 1em 2em` — The first value represents the top left and bottom right corner, the second the top right and bottom left ones.
	The 3-value syntax: `border-radius: 1em 2em 3em` — The first value represents the top left corner, the second the top right and bottom left ones, and the third value the bottom right corner
	The 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

A background with the following properties ...

background-color: #000;
background-image: url(images/bg.gif);
background-repeat: no-repeat;
background-position: left top;

... can be shortened to just one declaration:

background: #000 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

The following declarations ...

font-style: italic;
font-weight: bold;
font-size: .8em;
line-height: 1.2;
font-family: Arial, sans-serif;

... can be shortened to the following:

font: italic bold .8em/1.2 Arial, sans-serif;

This shorthand declaration is actually equivalent to the longhand declarations above plus font-variant: normal and font-size-adjust: none (CSS2.0 / CSS3), font-stretch: normal (CSS3).

Border properties

With borders, the width, color, and style can be simplified into one declaration. For example, the following CSS ...

border-width: 1px;
border-style: solid;
border-color: #000;

... can be simplified as:

border: 1px solid #000;

Margin and padding properties

Shorthand versions of margin and padding values work the same way. The following CSS declarations ...

margin-top: 10px;
margin-right: 5px;
margin-bottom: 10px;
margin-left: 5px;

... are the same as the following declaration. 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;

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 to one of:

CSS provides four special universal property values for specifying inheritance:

inherit: Sets the property value applied to a selected element to be the same as that of its parent element.
initial: Sets the property value applied to a selected element to be the same as the value set for that element in the browser's default style sheet. If no value is set by the browser's default style sheet and the property is naturally inherited, then the property value is set to inherit instead.
unset: Resets the property to its natural value, which means that if the property is naturally inherited it acts like inherit, otherwise it acts like initial.
revert: Reverts the property to the value it would have had if the current origin had not applied any styles to it. In other words, the property's value is set to the user stylesheet's value for the property (if one is set), otherwise, the property's value is taken from the user agent's default stylesheet.

See Origin of CSS declarations in Introducing the CSS Cascade for more information on each of these and how they work.

Note: initial and unset are not supported in Internet Explorer.

Of these, inherit is frequently the most interesting — it allows us to explicitly make an element inherit a property value from its parent.

Let's take a look at an example. First some HTML:

<ul>
  <li>Default <a href="#">link</a> color</li>
  <li class="my-class-1">Inherit the <a href="#">link</a> color</li>
  <li class="my-class-2">Reset the <a href="#">link</a> color</li>
  <li class="my-class-3">Unset the <a href="#">link</a> color</li>
</ul>

Now some CSS for styling:

body {
  color: green;
}

.my-class-1 a {
  color: inherit;
}

.my-class-2 a {
  color: initial;
}

.my-class-3 a {
  color: unset;
}

Result:

Let's explain what's going on here:

We first set the color of the <body> to green.
As the color property is naturally inherited, all child elements of body will have the same green color. It's worth noting that browsers set the color of links to blue by default instead of allowing the natural inheritance of the color property, so the first link in our list is blue.
The second rule sets links within an element with the class my-class-1 to inherit its color from its parent. In this case, it means that the link inherits its color from its <li> parent, which, by default inherits its color from its own <ul> parent, which ultimately inherits its color from the <body> element, which had its color set to green by the first rule.
The third rule selects any links within an element with the class my-class-2 and sets their color to initial. Usually, the initial value set by browsers for the text color is black, so this link is set to black.
The last rule selects all links within an element with the class my-class-3 and sets their color to unset — we unset the value. Because the color property is a naturally inherited property it acts exactly like setting the value to inherit. As a consequence, this link is set to the same color as the body — green.

See Cascade and inheritance or Introducing the CSS Cascade for more information about how inheritance works in CSS.