By default, components generated by the library (Box, Composition, and area components) render a <div> element, which may not be a valid HTML element in some use cases.
You can provide a custom HTML element or a React component to render instead of the default one by using polymorphic prop styled-components feature.
See Polymorphic prop API in styled components' documentation.

Using HTML element

To render a different HTML element provide its name as a value of the as prop of any component exported or generated by the library:
import React from 'react'
import { Box } from 'atomic-layout'
export const Header = (props) => (
<Box as="header" {...props} />

Using React component

To render a custom React component provide its reference as a value to the as prop.
You must spread the props in your custom component to propagate class names generated by styled-components.
import React from 'react'
import { Box } from 'atomic-layout'
import styled from 'styled-components'
const Header = (props) => (
// Spreading the props assigns "className" (SC)
// and the props from Atomic Layout.
<div {...props} />
export const MyComponent = () => (
<Box as={Header} height={50} padding={10} />

Custom areas components

Polymorphic prop can be used on the area components generated by Composition.
import React from 'react'
import { Composition } from 'atomic-layout'
import { Footer as CustomFooter } from '@components'
export const PageContent = () => (
<Composition as="main" areas="header footer">
{(Areas) => (
<Areas.Header as="header">{...}</Areas.Header>
<Areas.Footer as={CustomFooter}>{...}</Areas.Footer>