border-image-source

The border-image-source CSS property defines the <image> (en-US) to use instead of the style of the border. If this property is set to none, the style defined by border-style (en-US) is used instead.

/* no border-image, use the specified border-style */
border-image-source: none;

/* the image.jpg is used as image */
border-image-source: url(image.jpg);

/* a gradient is used as image */
border-image-source: linear-gradient(to top, red, yellow);

/* Global values */
border-image-source: inherit;
border-image-source: initial;
border-image-source: unset;

none

Specifies that no image should be used for the border. Instead the style defined by border-style (en-US) is used.

<image>

Ссылка на изображение, которое будет использоваться в отрисовке границы.

none | (en-US) <image> (en-US)
где 
<image> = <url> | (en-US) <image()> | (en-US) <image-set()> | (en-US) <element()> | (en-US) <paint()> | (en-US) <cross-fade()> | (en-US) <gradient>
где 
<image()> = image( <image-tags>? (en-US) [ (en-US) <image-src>? (en-US) , <color>? (en-US) ] (en-US)! (en-US) )
<image-set()> = image-set( <image-set-option># (en-US) )
<element()> = element( <id-selector> )
<paint()> = paint( <ident> (en-US), <declaration-value>? (en-US) )
<cross-fade()> = cross-fade( <cf-mixing-image> , <cf-final-image>? (en-US) )
<gradient> = <linear-gradient()> | (en-US) <repeating-linear-gradient()> | (en-US) <radial-gradient()> | (en-US) <repeating-radial-gradient()> | (en-US) <conic-gradient()>
где 
<image-tags> = ltr | (en-US) rtl
<image-src> = <url> | (en-US) <string> (en-US)
<color> = <rgb()> | (en-US) <rgba()> | (en-US) <hsl()> | (en-US) <hsla()> | (en-US) <hex-color> | (en-US) <named-color> | (en-US) currentcolor | (en-US) <deprecated-system-color>
<image-set-option> = [ (en-US) <image> (en-US) | (en-US) <string> (en-US) ] (en-US) <resolution> (en-US)
<id-selector> = <hash-token>
<cf-mixing-image> = <percentage>? (en-US) && (en-US) <image> (en-US)
<cf-final-image> = <image> (en-US) | (en-US) <color>
<linear-gradient()> = linear-gradient( [ (en-US) <angle> | (en-US) to <side-or-corner> ] (en-US)? (en-US) , <color-stop-list> )
<repeating-linear-gradient()> = repeating-linear-gradient( [ (en-US) <angle> | (en-US) to <side-or-corner> ] (en-US)? (en-US) , <color-stop-list> )
<radial-gradient()> = radial-gradient( [ (en-US) <ending-shape> || (en-US) <size> ] (en-US)? (en-US) [ (en-US) at <position> (en-US) ] (en-US)? (en-US) , <color-stop-list> )
<repeating-radial-gradient()> = repeating-radial-gradient( [ (en-US) <ending-shape> || (en-US) <size> ] (en-US)? (en-US) [ (en-US) at <position> (en-US) ] (en-US)? (en-US) , <color-stop-list> )
<conic-gradient()> = conic-gradient( [ (en-US) from <angle> ] (en-US)? (en-US) [ (en-US) at <position> (en-US) ] (en-US)? (en-US), <angular-color-stop-list> )
где 
<rgb()> = rgb( <percentage>{ (en-US)3} (en-US) [ (en-US) / <alpha-value> ] (en-US)? (en-US) ) | (en-US) rgb( <number>{ (en-US)3} (en-US) [ (en-US) / <alpha-value> ] (en-US)? (en-US) ) | (en-US) rgb( <percentage># (en-US){ (en-US)3} (en-US) , <alpha-value>? (en-US) ) | (en-US) rgb( <number># (en-US){ (en-US)3} (en-US) , <alpha-value>? (en-US) )
<rgba()> = rgba( <percentage>{ (en-US)3} (en-US) [ (en-US) / <alpha-value> ] (en-US)? (en-US) ) | (en-US) rgba( <number>{ (en-US)3} (en-US) [ (en-US) / <alpha-value> ] (en-US)? (en-US) ) | (en-US) rgba( <percentage># (en-US){ (en-US)3} (en-US) , <alpha-value>? (en-US) ) | (en-US) rgba( <number># (en-US){ (en-US)3} (en-US) , <alpha-value>? (en-US) )
<hsl()> = hsl( <hue> <percentage> <percentage> [ (en-US) / <alpha-value> ] (en-US)? (en-US) ) | (en-US) hsl( <hue>, <percentage>, <percentage>, <alpha-value>? (en-US) )
<hsla()> = hsla( <hue> <percentage> <percentage> [ (en-US) / <alpha-value> ] (en-US)? (en-US) ) | (en-US) hsla( <hue>, <percentage>, <percentage>, <alpha-value>? (en-US) )
<side-or-corner> = [ (en-US) left | (en-US) right ] (en-US) || (en-US) [ (en-US) top | (en-US) bottom ] (en-US)
<color-stop-list> = [ (en-US) <linear-color-stop> [ (en-US), <linear-color-hint>] (en-US)? (en-US) ] (en-US)# (en-US) , <linear-color-stop>
<ending-shape> = circle | (en-US) ellipse
<size> = closest-side | (en-US) farthest-side | (en-US) closest-corner | (en-US) farthest-corner | (en-US) <length> | (en-US) <length-percentage>{ (en-US)2} (en-US)
<position> = [ (en-US) [ (en-US) left | (en-US) center | (en-US) right ] (en-US) || (en-US) [ (en-US) top | (en-US) center | (en-US) bottom ] (en-US) | (en-US) [ (en-US) left | (en-US) center | (en-US) right | (en-US) <length-percentage> ] (en-US) [ (en-US) top | (en-US) center | (en-US) bottom | (en-US) <length-percentage> ] (en-US)? (en-US) | (en-US) [ (en-US) [ (en-US) left | (en-US) right ] (en-US) <length-percentage> ] (en-US) && (en-US) [ (en-US) [ (en-US) top | (en-US) bottom ] (en-US) <length-percentage> ] (en-US) ] (en-US)
<angular-color-stop-list> = [ (en-US) <angular-color-stop> [ (en-US), <angular-color-hint>] (en-US)? (en-US) ] (en-US)# (en-US) , <angular-color-stop>
где 
<alpha-value> = <number> | (en-US) <percentage>
<hue> = <number> | (en-US) <angle>
<linear-color-stop> = <color> <color-stop-length>? (en-US)
<linear-color-hint> = <length-percentage>
<length-percentage> = <length> | (en-US) <percentage>
<angular-color-stop> = <color> && (en-US) <color-stop-angle>? (en-US)
<angular-color-hint> = <angle-percentage>
где 
<color-stop-length> = <length-percentage>{ (en-US)1,2} (en-US)
<color-stop-angle> = <angle-percentage>{ (en-US)1,2} (en-US)
<angle-percentage> = <angle> | (en-US) <percentage>

See border-image (en-US) for examples of what the various source values will do.