fix(spa): fallback font-serif to Prompt for Thai characters

apps/spa/tailwind.config.js

@@ -9,6 +9,10 @@ export default {
       fontFamily: {
         sans: ['Sarabun', 'sans-serif'],
         heading: ['Prompt', 'sans-serif'],
+        serif: ['ui-serif', 'Georgia', 'Cambria', '"Times New Roman"', 'Times', 'Prompt', 'serif'],
+        'sans-ja': ['"Noto Sans JP"', 'sans-serif'],
+        'sans-zh': ['"Noto Sans SC"', 'sans-serif'],
+        'sans-ko': ['"Noto Sans KR"', 'sans-serif'],
       },
       colors: {
         pop: {