Set font sizes for typography elements

frontend/src/themes/main.ts

@@ -10,6 +10,19 @@ const mainTheme: ThemeOptions = {
     textWhite: 'white',
     footerLinkBgColor: '#202020',
   },
+  typography: {
+    fontSize: 16,
+    h2: {
+      fontSize: 28,
+    },
+    body1: {
+      fontSize: 18,
+    },
+    button: {
+      fontSize: 14,
+    },
+  },
+
   // No palette section defined here, it is up to the different institutions to define colours that override the default ones from Material UI
   components: {
     MuiTextField: {