chore: re-configure rollup-plugin-svelte

...  after breaking update.

Re-aligned the configuration as demonstrated
[here](https://github.com/sveltejs/template/blob/5b1135c286f7a649daa99825a077586655051649/rollup.config.js#L48).

The breaking changes were:
* [removing CSS extraction](sveltejs/rollup-plugin-svelte#147)
* [nesting compiler options in key](sveltejs/rollup-plugin-svelte#145)

Author: philipp-tailor

package.json

@@ -28,6 +28,7 @@
 		"prettier-plugin-svelte": "^2.1.4",
 		"rollup": "^2.38.5",
 		"rollup-plugin-commonjs": "^10.1.0",
+		"rollup-plugin-css-only": "^3.1.0",
 		"rollup-plugin-livereload": "^2.0.0",
 		"rollup-plugin-md": "^1.0.1",
 		"rollup-plugin-node-resolve": "^5.2.0",

rollup.config.js

@@ -2,6 +2,7 @@ import svelte from 'rollup-plugin-svelte'
 import resolve from 'rollup-plugin-node-resolve'
 import commonjs from 'rollup-plugin-commonjs'
 import md from 'rollup-plugin-md'
+import css from 'rollup-plugin-css-only'
 import livereload from 'rollup-plugin-livereload'
 import { terser } from 'rollup-plugin-terser'
 import visualizer from 'rollup-plugin-visualizer'
@@ -19,14 +20,14 @@ export default {
 	},
 	plugins: [
 		svelte({
-			// enable run-time checks when not in production
-			dev: !production,
-			// we'll extract any component CSS out into
-			// a separate file — better for performance
-			css: (css) => {
-				css.write('bundle.css')
+			compilerOptions: {
+				// enable run-time checks when not in production
+				dev: !production,
 			},
 		}),
+		// we'll extract any component CSS out into
+		// a separate file - better for performance
+		css({ output: 'bundle.css' }),
 
 		// If you have external dependencies installed from
 		// npm, you'll most likely need these plugins. In

yarn.lock

@@ -44,6 +44,14 @@
     "@nodelib/fs.scandir" "2.1.3"
     fastq "^1.6.0"
 
+"@rollup/pluginutils@4":
+  version "4.1.0"
+  resolved "https://registry.yarnpkg.com/@rollup/pluginutils/-/pluginutils-4.1.0.tgz#0dcc61c780e39257554feb7f77207dceca13c838"
+  integrity sha512-TrBhfJkFxA+ER+ew2U2/fHbebhLT/l/2pRk0hfj9KusXUuRXd2v0R58AfaZK9VXDQ4TogOSEmICVrQAA3zFnHQ==
+  dependencies:
+    estree-walker "^2.0.1"
+    picomatch "^2.2.2"
+
 "@types/color-name@^1.1.1":
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/@types/color-name/-/color-name-1.1.1.tgz#1c1261bbeaa10a8055bbc5d8ab84b7b2afc846a0"
@@ -527,6 +535,11 @@ estree-walker@^0.6.1:
   resolved "https://registry.yarnpkg.com/estree-walker/-/estree-walker-0.6.1.tgz#53049143f40c6eb918b23671d1fe3219f3a1b362"
   integrity sha512-SqmZANLWS0mnatqbSfRP5g8OXZC12Fgg1IwNtLsyHDzJizORW4khDfjPqJZsemPWBB2uqykUah5YpQ6epsqC/w==
 
+estree-walker@^2.0.1:
+  version "2.0.2"
+  resolved "https://registry.yarnpkg.com/estree-walker/-/estree-walker-2.0.2.tgz#52f010178c2a4c117a7757cfe942adb7d2da4cac"
+  integrity sha512-Rfkk/Mp/DL7JVje3u18FxFujQlTNR2q6QfMSMB7AvCBx91NGj/ba3kCfza0f6dVDbw7YlRf/nDrn7pQrCCyQ/w==
+
 execa@^0.7.0:
   version "0.7.0"
   resolved "https://registry.yarnpkg.com/execa/-/execa-0.7.0.tgz#944becd34cc41ee32a63a9faf27ad5a65fc59777"
@@ -1162,7 +1175,7 @@ path-type@^4.0.0:
   resolved "https://registry.yarnpkg.com/path-type/-/path-type-4.0.0.tgz#84ed01c0a7ba380afe09d90a8c180dcd9d03043b"
   integrity sha512-gDKb8aZMDeD/tZWs9P6+q0J9Mwkdl6xMV8TjnGP3qJVJ06bdMgkbBlLU8IdfOsIsFz2BW1rNVT3XuNEl8zPAvw==
 
-picomatch@^2.0.4, picomatch@^2.0.7, picomatch@^2.2.1:
+picomatch@^2.0.4, picomatch@^2.0.7, picomatch@^2.2.1, picomatch@^2.2.2:
   version "2.2.2"
   resolved "https://registry.yarnpkg.com/picomatch/-/picomatch-2.2.2.tgz#21f333e9b6b8eaff02468f5146ea406d345f4dad"
   integrity sha512-q0M/9eZHzmr0AulXyPwNfZjtwZ/RBZlbN3K3CErVrk50T2ASYI7Bye0EvekFY3IP1Nt2DHu0re+V2ZHIpMkuWg==
@@ -1309,6 +1322,13 @@ rollup-plugin-commonjs@^10.1.0:
     resolve "^1.11.0"
     rollup-pluginutils "^2.8.1"
 
+rollup-plugin-css-only@^3.1.0:
+  version "3.1.0"
+  resolved "https://registry.yarnpkg.com/rollup-plugin-css-only/-/rollup-plugin-css-only-3.1.0.tgz#6a701cc5b051c6b3f0961e69b108a9a118e1b1df"
+  integrity sha512-TYMOE5uoD76vpj+RTkQLzC9cQtbnJNktHPB507FzRWBVaofg7KhIqq1kGbcVOadARSozWF883Ho9KpSPKH8gqA==
+  dependencies:
+    "@rollup/pluginutils" "4"
+
 rollup-plugin-livereload@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/rollup-plugin-livereload/-/rollup-plugin-livereload-2.0.0.tgz#d3928d74e8cf2ae4286c5dd46b770fd3f3b82313"