UglifyJs output line length restriction

Question

I am using the following snippets while building my react based application with webpack. I need to restrict the max line length of the output file to 7000 characters and the below config helps do it except if there is a CSS line in the bundle. The CSS line comes in a string literal and it goes beyond this restriction. How do I make the restriction applied to CSS embedded within the bundle?

new Webpack.optimize.UglifyJsPlugin({
  compress: {
    warnings: false
  },
  output: {
    comments: false,
    max_line_len: 7000
  },
  sourceMap: false
})

A task which is used during the build from npm -

UglifyJS.minify([ ... ], {
                                                            output: {                
                                                                max_line_len: 7000
                                                              }
                                                        });