Add a mixin to be able to fetch the values from CSS variables.

src/main.js

@@ -3,6 +3,16 @@ import App from './App.vue';
 
 Vue.config.productionTip = false;
 
+// global mixings
+Vue.mixin({
+	methods: {
+		css_var(var_name) {
+			return getComputedStyle(document.documentElement).getPropertyValue(var_name);
+		},
+	}
+});
+
+
 // eslint-disable-next-line
 const app = new Vue({
 	render: h => h(App),