Using Sass

Instead of using plain CSS, let's switch to Sass:

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$ mv assets/styles/app.css assets/styles/app.scss

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--- a/assets/app.js
+++ b/assets/app.js
@@ -6,7 +6,7 @@
  */

 // any CSS you import will output into a single css file (app.css in this case)
-import './styles/app.css';
+import './styles/app.scss';

 // start the Stimulus application
 import './bootstrap';

Install the Sass loader:

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$ npm install node-sass sass-loader --save-dev

And enable the Sass loader in webpack:

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--- a/webpack.config.js
+++ b/webpack.config.js
@@ -57,7 +57,7 @@ Encore
     })

     // enables Sass/SCSS support
-    //.enableSassLoader()
+    .enableSassLoader()

     // uncomment if you use TypeScript
     //.enableTypeScriptLoader()

How did I know which packages to install? If we had tried to build our assets without them, Encore would have given us a nice error message suggesting the npm install command needed to install dependencies to load .scss files.

Leveraging Bootstrap

To start with good defaults and build a responsive website, a CSS framework like Bootstrap can go a long way. Install it as a package:

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$ npm install bootstrap @popperjs/core bs-custom-file-input --save-dev

Require Bootstrap in the CSS file (we have also cleaned up the file):

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--- a/assets/styles/app.scss
+++ b/assets/styles/app.scss
@@ -1,3 +1 @@
-body {
-    background-color: lightgray;
-}
+@import '~bootstrap/scss/bootstrap';

Do the same for the JS file:

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--- a/assets/app.js
+++ b/assets/app.js
@@ -7,6 +7,10 @@

 // any CSS you import will output into a single css file (app.css in this case)
 import './styles/app.scss';
+import 'bootstrap';
+import bsCustomFileInput from 'bs-custom-file-input';

 // start the Stimulus application
 import './bootstrap';
+
+bsCustomFileInput.init();

The Symfony form system supports Bootstrap natively with a special theme, enable it:

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twig:
    form_themes: ['bootstrap_5_layout.html.twig']

Styling the HTML

We are now ready to style the application. Download and expand the archive at the root of the project:

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$ php -r "copy('https://symfony.com/uploads/assets/guestbook-6.2.zip', 'guestbook-6.2.zip');"
$ unzip -o guestbook-6.2.zip
$ rm guestbook-6.2.zip

Have a look at the templates, you might learn a trick or two about Twig.

Building Assets

One major change when using Webpack is that CSS and JS files are not usable directly by the application. They need to be "compiled" first.

In development, compiling the assets can be done via the encore dev command:

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$ symfony run npm run dev

Instead of executing the command each time there is a change, send it to the background and let it watch JS and CSS changes:

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$ symfony run -d npm run watch

Take the time to discover the visual changes. Have a look at the new design in a browser.

The generated login form is now styled as well as the Maker bundle uses Bootstrap CSS classes by default:

For production, Platform.sh automatically detects that you are using Encore and compiles the assets for you during the build phase.