--- url: /docs/guide/usage/linter/rules/nextjs/no-styled-jsx-in-document.md --- ### What it does Prevent usage of styled-jsx in `pages/_document.js`. ### Why is this bad? Custom CSS like styled-jsx is not allowed in a [Custom Document](https://nextjs.org/docs/pages/building-your-application/routing/custom-document). ### Examples Examples of **incorrect** code for this rule: ```javascript // pages/_document.js import Document, { Html, Head, Main, NextScript } from "next/document"; class MyDocument extends Document { render() { return (

); } } ``` Examples of **correct** code for this rule: ```javascript // pages/_document.js import Document, { Html, Head, Main, NextScript } from "next/document"; class MyDocument extends Document { render() { return (

); } } ``` ## How to use ## Version This rule was added in v0.3.3. ## References