replace all stylesheets with tailwind classes

apps/mobile/app/_layout.tsx

@@ -10,7 +10,7 @@ import { SplashScreen, Stack } from 'expo-router';
 import { useEffect } from 'react';
 import { useColorScheme } from 'react-native';
 
-import Colors from '../constants/Colors.js';
+import useTailwind from './hooks/useTailwind';
 
 export {
   // Catch any errors thrown by the Layout component.
@@ -57,6 +57,7 @@ export default function RootLayout() {
 
 function RootLayoutNav() {
   const colorScheme = useColorScheme();
+  const { colors } = useTailwind();
 
   return (
     <ThemeProvider value={colorScheme === 'dark' ? DarkTheme : DefaultTheme}>
@@ -65,7 +66,7 @@ function RootLayoutNav() {
           gestureEnabled: true,
           headerShown: false,
           contentStyle: {
-            backgroundColor: Colors.shade[900],
+            backgroundColor: colors.shade[900],
           },
         }}
       >