border-left-color

/* <color> values */
border-left-color: red;
border-left-color: #ffbb00;
border-left-color: rgb(255, 0, 0);
border-left-color: hsla(100%, 50%, 25%, 0.75);
border-left-color: currentcolor;
border-left-color: transparent;

/* Global values */
border-left-color: inherit;
border-left-color: initial;
border-left-color: revert;
border-left-color: revert-layer;
border-left-color: unset;

The border-left-color property is specified as a single value.

<color>

The color of the left border.

border-left-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

<div class="mybox">
  <p>This is a box with a border around it.
     Note which side of the box is
     <span class="redtext">red</span>.</p>
</div>

CSS

.mybox {
    border: solid 0.3em gold;
    border-left-color: red;
    width: auto;
}

.redtext {
    color: red;
}

Result

• The border-related CSS shorthand properties: border, border-left, and border-color.
• The color-related CSS properties for the other borders: border-right-color, border-bottom-color, and border-top-color.
• The other border-related CSS properties applying to the same border: border-left-style and border-left-width.