mask-border-outset CSS property.

Values: [ <length> | <number> ]{1,4}
Initial value: 0
Applies to: All elements. In SVG, it applies to container elements excluding the <defs> element and all graphics elements
Inherit: no
Percentages: n/a
Animatable: no
Media: visual
Computed value: all <length>s made absolute, otherwise as specified

CSS Standards

CSS 1
CSS 2
CSS 2.1
CSS 3
Yes