src/themes/default/base/_spacing.scss
// ===========================================
// Spacing - Default Theme
// ===========================================
$theme-spacing: 6px !default;
$margin-tool-base: $theme-spacing;
$spacing-tool-base: $theme-spacing;
$theme-spacing-variants: (
none: 0,
x-small: .5,
small: 1,
medium: 2,
large: 3,
x-large: 4,
xx-large: 5
) !default;
$theme-margin-variants: $theme-spacing-variants !default;
$theme-padding-variants: $theme-spacing-variants !default;