import React from 'react' ; import styled from '@emotion/styled' ; const Box = styled ( 'div' ) ( ( props ) => ( { display : 'inline-block' , width : 100 , height : 100 , backgroundColor : '$gray400' , textAlign : 'center' , lineHeight : 1 , fontSize : 100 , ... props . css , } ) ) ; export default function App ( ) { return ( < > < h1 > Emotion < /h1> { Array ( 500 ) . fill ( 1 ) . map ( ( _ , i ) => ( < Box css = { { margin : i + 'px' } } key = { i } > { i } < /Box>))} < />); }