You can easily use TypeStyle to build static html files with encapsulated CSS. You can use this pattern to generate email and pdf template files. Since TypeStyle supports cssRaw all your css can be easily inlined into a single file making it easy to work with template rendering engines.
import {style, getStyles} from "typestyle";
import * as React from "react";
const className = style({
color: 'red',
fontSize: '30px'
});
const App = () =>
<div className={className}>
Hello World!
</div>;
import * as ReactDOMServer from 'react-dom/server';
const html = ReactDOMServer.renderToStaticMarkup(<App />);
const css = getStyles();
const renderPage = ({html, css}) => `
<html>
<header>
<style>${css}</style>
</header>
<body>
<div>${html}</div>
</body>
</html>
`;
const renderedPage = renderPage({html, css});
import * as fs from 'fs';
fs.writeFileSync(__dirname + '/index.html', renderedPage);