diff --git a/ui/webpack/base.js b/ui/webpack/base.js
index 915b1de1..f4d0256f 100644
--- a/ui/webpack/base.js
+++ b/ui/webpack/base.js
@@ -17,11 +17,16 @@ const plugins = {
           require('postcss-modules-values'),
           require('postcss-functions')({
             functions: {
-              remCalc: function(pixels) {
-                pixels = pixels.replace('px', '');
-                const baseValue = 16;
-                const remSize = pixels / baseValue;
-                return `${remSize}rem`;
+              remCalc: function(values) {
+                values = values.replace('px', '');
+                values = values.split(' ');
+                let outputRems = '';
+                const base = 16;
+                values.forEach( (value, i) => {
+                  const remValue = value / base;
+                  outputRems += i === 0 ? `${remValue}rem` : ` ${remValue}rem`;
+                });
+                return outputRems;
               }
             },
           }),