fix(whiteboard): tldraw demo should inherit root tailwind config

tldraw/demo/postcss.config.js

@@ -1,3 +1,5 @@
+const rootTailwindConfig = require('../../tailwind.config')
+
 module.exports = {
   plugins: {
     'postcss-import': {},
@@ -5,6 +7,7 @@ module.exports = {
     'postcss-import-ext-glob': {},
     'tailwindcss/nesting': {},
     tailwindcss: {
+      ...rootTailwindConfig,
       content: ['./**/*.jsx', '../apps/**/*.{js,jsx,ts,tsx}'],
     },
     autoprefixer: {},