CSS column-rule

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The CSS column-rule property is a shorthand property for setting multiple column rule related properties in one place.

Specifically, the property sets the column-rule-width, column-rule-style, and column-rule-color properties.

The column rule appears as a kind of border that appears in between the columns on a multi-column layout.

The CSS column-rule property is a time-efficient way of adding a rule to your multi-column layouts.

Syntax

Possible Values

<column-rule-width>: Defines the width that the column rules should be. The values are the same as those allowed by the border-width property. The value can be either thin, medium, or thick, or it can be an explicit width (e.g., 5px). For more information on this value, see the column-width property.
<column-rule-style>: Defines the style for the column rule. The values are the same as those allowed by the border-style property and are none, hidden, dotted, dashed, solid, double, groove, ridge, inset, and outset. For more information on this value, see the column-rule-style property.
<column-rule-color>: Defines the color for the column rule. For more information on this value, see the column-rule-color property.

In addition, all CSS properties also accept the following CSS-wide keyword values as the sole component of their property value:

initial: Represents the value specified as the property's initial value.
inherit: Represents the computed value of the property on the element's parent.
unset: This value acts as either inherit or initial, depending on whether the property is inherited or not. In other words, it sets all properties to their parent value if they are inheritable or to their initial value if not inheritable.

Basic Property Information

Initial Value: See individual properties
Applies To: multicol elements
Inherited?: No
Media: Visual
Animatable: Yes (see example)

Example Code

Basic CSS

Working Example within an HTML Document

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This example uses vendor prefixes for the multi-column layout due to lack of browser support for the official standard at the time of writing.

CSS Specifications

The column-rule property is defined in CSS Multi-column Layout Module (W3C Candidate Recommendation 12 April 2011).

Browser Support

The following table provided by Caniuse.com shows the level of browser support for this feature.

Vendor Prefixes

For maximum browser compatibility many web developers add browser-specific properties by using extensions such as -webkit- for Safari, Google Chrome, and Opera (newer versions), -ms- for Internet Explorer, -moz- for Firefox, -o- for older versions of Opera etc. As with any CSS property, if a browser doesn't support a proprietary extension, it will simply ignore it.

This practice is not recommended by the W3C, however in many cases, the only way you can test a property is to include the CSS extension that is compatible with your browser.

The major browser manufacturers generally strive to adhere to the W3C specifications, and when they support a non-prefixed property, they typically remove the prefixed version. Also, W3C advises vendors to remove their prefixes for properties that reach Candidate Recommendation status.

Many developers use Autoprefixer, which is a postprocessor for CSS. Autoprefixer automatically adds vendor prefixes to your CSS so that you don't need to. It also removes old, unnecessary prefixes from your CSS.

You can also use Autoprefixer with preprocessors such as Less and Sass.