fix rgba css generation, add some tests to automatically verify that themes are

generated properly

src/services/color_convert/color_convert.js

@@ -171,7 +171,7 @@ export const mixrgb = (a, b) => {
  * @returns {String} CSS rgba() color
  */
 export const rgba2css = function (rgba) {
-  return `rgba(${rgba.r}, ${rgba.g}, ${rgba.b}, ${rgba.a})`
+  return `rgba(${Math.floor(rgba.r)}, ${Math.floor(rgba.g)}, ${Math.floor(rgba.b)}, .5)`
 }
 
 /**

src/services/theme_data/theme_data.service.js

@@ -353,7 +353,7 @@ export const getColors = (sourceColors, sourceOpacity, mod) => SLOT_ORDERED.redu
     if (dependencySlot && sourceColors[dependencySlot] === 'transparent') {
       outputColor.a = 0
     } else {
-      outputColor.a = sourceOpacity[opacitySlot] || OPACITIES[opacitySlot].defaultValue || 1
+      outputColor.a = Number(sourceOpacity[opacitySlot]) || OPACITIES[opacitySlot].defaultValue || 1
     }
   }
   if (opacitySlot) {