Error with postcss plugin
This a log when I tried a ng build --prod, I' using angular universal only give me that error with bootstrap and font-awesome.
10% building modules 4/6 modules 2 active ...ules/bootstrap/dist/css/bootstrap.cssUnknown error from PostCSS plugin. Your current PostCSS version is 6.0.17, but postcss-merge-rules uses 5.2.18. Perhaps this i 55% building modules 380/383 modules 3 active ...ules/bootstrap/dist/css/bootstrap.cssUnknown error from PostCSS plugin. Your current PostCSS version is 6.0.17, but postcss-merge-rules uses 5.2.18. Perhaps this is the source of the error below.
I had the same problem, you should update you angular cli version to the latest beta, run this command:
at first install it globally :
npm install -g @angular/cli@1.7.0-beta.1
// then you should update your current project:
npm install --save-dev @angular/cli@1.7.0-beta.1
来源：https://stackoverflow.com/questions/48713063/why-postcss-merge-rules-vesion-give-me-an-error-angular-5-webpack