column-rule-width

The column-rule-width CSS property defines the widths of the lines drawn between columns in multi-column grid, flex, and multi-col layouts.

The column-rule-width property defines the widths of any column rule lines drawn in the gutters between adjacent columns in multi-column, flex, and grid containers with more than one column.

Note: The column-rule-width only defines the width of the lines painted in the gaps. These lines have no effect on the box model or layout. The size of the gutter is defined by the gap property; with the default value being 1em on multi-column containers and 0 in all other contexts. If the width of a rule is wider than the gap, the line will be painted behind the column content.

Syntax example: column-rule-width: thin;