update App layout

swlab-main/src/App.jsx

 // @ts-nocheck
 import './styles/index.scss'
+import styled from 'styled-components'
 import Banner from './components/Banner'
 import Header from './components/Header'
 import Section from './components/Section'
@@ -8,7 +9,8 @@ import Footer from './components/Footer'
 
 function App () {
   return (
-    <>
+    <Root>
+      <Main>
         <Header />
         <Banner />
         <Section title='Products' gap='3rem' display='grid'>
@@ -61,9 +63,20 @@ function App () {
               '다양한 모니터링',
             ]}/>
         </Section>
+      </Main>
       <Footer />
-    </>
+    </Root>
   )
 }
 
+const Root = styled.div`
+  display: flex;
+  flex-direction: column;
+  width: 100%;
+  height: 100%;
+`
+const Main = styled.main`
+  flex-grow: 1;
+`
+
 export default App