column-rule-color

css

/* Значения <color>  */
column-rule-color: red;
column-rule-color: rgb(192, 56, 78);
column-rule-color: transparent;
column-rule-color: hsla(0, 100%, 50%, 0.6);

/* Глобальные значения */
column-rule-color: inherit;
column-rule-color: initial;
column-rule-color: unset;

html

<p>
  This is a bunch of text split into three columns. The `column-rule-color`
  property is used to change the color of the line that is drawn between
  columns. Don't you think that's wonderful?
</p>

css

p {
  column-count: 3;
  column-rule-style: solid;
  column-rule-color: blue;
}