npm install --save styled-components

import styled from 'styled-components';

import { injectGlobal } from 'styled-components'

export const NavSearch = styled.input.attrs({

    placeholder: '搜索'

})`

    width: 160px;

    height: 38px;

    &::placeholder {

        color: #999;

    }

`;

//全局样式

injectGlobal `

    body {

      margin: 0;

      padding: 0;

      font-family: sans-serif;

    }

`

<StyledView>

    <StyledText> Hello Marno! </StyledText>

</StyledView>