column-rule-color

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

/* Global values */
column-rule-color: inherit;
column-rule-color: initial;
column-rule-color: revert;
column-rule-color: revert-layer;
column-rule-color: unset;

The column-rule-color property is specified as a single <color> value.

<color>

The color of the rule that separates columns.

column-rule-color = 
  <color>  

<color> = 
  <absolute-color-base>  |
  currentcolor           |
  <system-color>         

<absolute-color-base> = 
  <hex-color>                |
  <absolute-color-function>  |
  <named-color>              |
  transparent                

<absolute-color-function> = 
  <rgb()>    |
  <rgba()>   |
  <hsl()>    |
  <hsla()>   |
  <hwb()>    |
  <lab()>    |
  <lch()>    |
  <oklab()>  |
  <oklch()>  |
  <color()>  

<rgb()> = 
  rgb( [ <percentage> | none ]{3} [ / [ <alpha-value> | none ] ]? )  |
  rgb( [ <number> | none ]{3} [ / [ <alpha-value> | none ] ]? )  

<hsl()> = 
  hsl( [ <hue> | none ] [ <percentage> | none ] [ <percentage> | none ] [ / [ <alpha-value> | none ] ]? )  

<hwb()> = 
  hwb( [ <hue> | none ] [ <percentage> | none ] [ <percentage> | none ] [ / [ <alpha-value> | none ] ]? )  

<lab()> = 
  lab( [ <percentage> | <number> | none ] [ <percentage> | <number> | none ] [ <percentage> | <number> | none ] [ / [ <alpha-value> | none ] ]? )  

<lch()> = 
  lch( [ <percentage> | <number> | none ] [ <percentage> | <number> | none ] [ <hue> | none ] [ / [ <alpha-value> | none ] ]? )  

<oklab()> = 
  oklab( [ <percentage> | <number> | none ] [ <percentage> | <number> | none ] [ <percentage> | <number> | none ] [ / [ <alpha-value> | none ] ]? )  

<oklch()> = 
  oklch( [ <percentage> | <number> | none ] [ <percentage> | <number> | none ] [ <hue> | none ] [ / [ <alpha-value> | none ] ]? )  

<color()> = 
  color( <colorspace-params> [ / [ <alpha-value> | none ] ]? )  

<alpha-value> = 
  <number>      |
  <percentage>  

<hue> = 
  <number>  |
  <angle>   |
  none      

<colorspace-params> = 
  <predefined-rgb-params>  |
  <xyz-params>             

<predefined-rgb-params> = 
  <predefined-rgb> [ <number> | <percentage> | none ]{3}  

<xyz-params> = 
  <xyz-space> [ <number> | none ]{3}  

<predefined-rgb> = 
  srgb          |
  srgb-linear   |
  display-p3    |
  a98-rgb       |
  prophoto-rgb  |
  rec2020       

<xyz-space> = 
  xyz      |
  xyz-d50  |
  xyz-d65  

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;
}

Result

• The <color> data type
• Other color-related properties: color, background-color, border-color, outline-color, text-decoration-color, text-emphasis-color, text-shadow, and caret-color
• Applying color to HTML elements using CSS