docs(guides): highlight css splitting in production

Resolves #1741

Author: skipjack

src/content/guides/asset-management.md

@@ -137,7 +137,7 @@ bundle.js  560 kB       0  [emitted]  [big]  main
 
 Open up `index.html` in your browser again and you should see that `Hello webpack` is now styled in red. To see what webpack did, inspect the page (don't view the page source, as it won't show you the result) and look at the page's head tags. It should contain our style block that we imported in `index.js`.
 
-T> Note that you can also [split your CSS](/plugins/extract-text-webpack-plugin) for better load times in production. On top of that, loaders exist for pretty much any flavor of CSS you can think of -- [postcss](/loaders/postcss-loader), [sass](/loaders/sass-loader), and [less](/loaders/less-loader) to name a few.
+Note that you can, and in most cases should, [split your CSS](/plugins/extract-text-webpack-plugin) for better load times in production. On top of that, loaders exist for pretty much any flavor of CSS you can think of -- [postcss](/loaders/postcss-loader), [sass](/loaders/sass-loader), and [less](/loaders/less-loader) to name a few.
 
 
 ## Loading Images

src/content/guides/production.md

@@ -182,6 +182,7 @@ __webpack.prod.js__
 
 T> Avoid `inline-***` and `eval-***` use in production as they can increase bundle size and reduce the overall performance.
 
+
 ## Specify the Environment
 
 Many libraries will key off the `process.env.NODE_ENV` variable to determine what should be included in the library. For example, when not in _production_ some libraries may add additional logging and testing to make debugging easier. However, with `process.env.NODE_ENV === 'production'` they might drop or add significant portions of code to optimize how things run for your actual users. We can use webpack's built in [`DefinePlugin`](/plugins/define-plugin) to define this variable for all our dependencies:
@@ -235,6 +236,11 @@ __src/index.js__
 ```
 
 
+## Split CSS
+
+As mentioned in __Asset Management__ at the end of the [Loading CSS](/guides/asset-management#loading-css) section, it is typically best practice to split your CSS out to a separate file using the `ExtractTextPlugin`. There are some good examples of how to do this in the plugin's [documentation](/plugins/extract-text-webpack-plugin). The `disable` option can be used in combination with the `--env` flag to allow inline loading in development, which is recommended for Hot Module Replacement and build speed.
+
+
 ## CLI Alternatives
 
 Some of what has been described above is also achievable via the command line. For example, the `--optimize-minimize` flag will include the `UglifyJSPlugin` behind the scenes. The `--define process.env.NODE_ENV="'production'"` will do the same for the `DefinePlugin` instance described above. And, `webpack -p` will automatically invoke both those flags and thus the plugins to be included.