refactor: migrate parcel to browserify

This also refactors a couple CSS stylesheets to be referenced directly in the
HTML files.

And it removes any CSS imports from src/browser files.

tsconfig.json

@@ -1,6 +1,6 @@
 {
   "compilerOptions": {
-    "target": "es5",
+    "target": "es2020",
     "module": "commonjs",
     "moduleResolution": "node",
     "strict": true,
@@ -8,7 +8,7 @@
     "noUnusedLocals": true,
     "forceConsistentCasingInFileNames": true,
     "outDir": "./out",
-    "declaration": true,
+    "declaration": false,
     "experimentalDecorators": true,
     "esModuleInterop": true,
     "allowSyntheticDefaultImports": true,