--- /dev/null
+@charset "UTF-8";
+
+/// Provides a concise, one-line method for setting `border-width` on specific
+/// edges of a box. Use a `null` value to “skip” edges of the box with standard
+/// CSS shorthand.
+///
+/// @argument {list} $values
+/// List of border widths; accepts CSS shorthand.
+///
+/// @example scss
+/// .element {
+/// @include border-width(1em null 20px);
+/// }
+///
+/// // CSS Output
+/// .element {
+/// border-bottom-width: 20px;
+/// border-top-width: 1em;
+/// }
+///
+/// @require {mixin} _directional-property
+
+@mixin border-width($values) {
+ @include _directional-property(border, width, $values);
+}