Adding globalStyled with styled components

# Changes

- adding global styles with styled components in _app.js

- Details

- Returns a StyledComponent that does not accept children. Place it at the top of your React tree and the global styles will be injected when the component is "rendered".
- Since the GlobalStyle component is a StyledComponent, that means it also has access to theming from the <ThemeProvider> component if provided.

examples/with-styled-components/pages/_app.js

@@ -1,5 +1,16 @@
+import { createGlobalStyle } from "styled-components";
 import { ThemeProvider } from 'styled-components'
 
+
+
+const GlobalStyle = createGlobalStyle`
+  body {
+    margin: 0;
+    padding: 0;
+    box-sizing: border-box;
+  }
+`;
+
 const theme = {
   colors: {
     primary: '#0070f3',
@@ -8,6 +19,7 @@ const theme = {
 
 export default function App({ Component, pageProps }) {
   return (
+     <GlobalStyle />
     <ThemeProvider theme={theme}>
       <Component {...pageProps} />
     </ThemeProvider>