In multi-column layouts, the column-rule CSS property specifies a straight line, or "rule", to be drawn between each column. It is a convenient shorthand to avoid setting each of the individual column-rule-* properties separately : column-rule-width, column-rule-style and column-rule-color.
Initial value the concatenation of the initial values of its longhand properties:
column-rule-color: If the value is translucent, the computed value will be the rgba() corresponding one. If it isn't, it will be the rgb() corresponding one. The transparent keyword maps to rgb(0,0,0).
column-rule-style: as specified
column-rule-width: an absolute length; 0 if the column rule style is none or hidden
Animatable as each of the properties of the shorthand: