column-gap

The column-gap CSS property sets the size of the gap between columns for elements which are specified to be displayed as multi-column elements.

/* Keyword value */
column-gap: normal; 
/* <length> values */
column-gap: 3px;
column-gap: 2.5em;
/* Global values */
column-gap: inherit;
column-gap: initial;
column-gap: unset;

Initial value	`normal`
Applies to	multicol elements
Inherited	no
Media	visual
Computed value	the absolute length or the keyword `normal`
Animation type	a length
Canonical order	the unique non-ambiguous order defined by the formal grammar

Syntax

The keyword normal, or a length.

Values

normal: Is a keyword indicating to use the browser-defined default spacing between columns. The specification, which most modern browsers follow, recommends that this be equal to a length of 1em.
<length>: Is a <length> value defining the size of the gap between columns. It must not be negative, but may be equal to 0.

Formal syntax

<length> | normal

Examples

.content-box {
  border: 10px solid #000000;
  column-count: 3;
  column-gap: 20px;
}

Specifications

Specification	Status	Comment
CSS Multi-column Layout Module The definition of 'column-gap' in that specification.	Candidate Recommendation	Initial definition

Feature	Chrome	Edge	Firefox (Gecko)	Internet Explorer	Opera	Safari (WebKit)
Basic support	(Yes)-webkit 50.0^[2]	(Yes)-webkit (Yes)	1.5 (1.8)-moz^[1] 52 (52)^[3]	10	11.10	3.0 (522)-webkit

Feature	Android	Android Webview	Edge	Firefox Mobile (Gecko)	IE Phone	Opera Mobile	Safari Mobile	Chrome for Android
Basic support	?	? 50.0^[2]	(Yes)-webkit (Yes)	(Yes) 52.0 (52)^[3]	?	?	?	? 50.0^[2]

[1] Before Firefox 3 (Gecko 1.9), the default value associated to the normal keyword was 0 and not 1em.

[2] Unprefixed as of Chrome 50.

[3] Unprefixed as of Gecko 52, with prefixed aliases still available.