Add the PostCSS pre-processor (https://postcss.org/) to improve the generated CSS bundles. The most straightforward way to go is to apply it the `webpack.config.js` file located under the `war` module

Plugins needed:

• Autoprefixer (https://github.com/postcss/autoprefixer)

Possible candidates

Some research is needed to determine if the following plugins are useful:

• Flexbugs fixes(https://github.com/luisrudge/postcss-flexbugs-fixes)