Investigate warning message when running yarn build:prod

[dkwon17]

When running yarn:prod, there is a warning message in the output:

WARNING in entrypoint size limit: The following entrypoint(s) combined asset size exceeds the recommended limit (244 KiB). This can impact web performance.
Entrypoints:
  options (620 KiB)
      options.css
      options.bundle.js

Investigate cause and possible fixes to the warning

[dkwon17]

The warning message is now hidden thanks to this PR: #45, but it is still worth investigating the issue (maybe webpack splitChunks will help)