add spacers() function

functions.js

@@ -7,6 +7,9 @@ const postcssFunctions = {
     const lightness = `var(${name}__l)`;
     return `hsla(${hue}, ${saturation}, ${lightness}, ${alpha})`;
   },
+  spacers(number = 1) {
+    return `calc(var(--spacer-height, 1.5rem) * ${number})`;
+  },
 };
 
 module.exports = postcssFunctions;