1-You must keep js files that you include in your index.html.
2- Scss files are not use in production (jst for dev).
3. You must keep css files that you include in your index.html.
Hey @Purusothaman this comes back to my question on the dev process and how we could possible decrease the app size when shipped. Ionic Dev Build Process
As for your app breaking. Make sure you are referencing the new .css file complied by Sass which should look like this in your index.html: