<!-- ch01-before-webpack/03-new-tech/emotion/index.html -->
<!DOCTYPE html>
<html>
<head>
<script src="https://unpkg.com/@emotion/css@11.1.3/dist/emotion-css.umd.min.js"></script>
</head>
<body>
<div id="root">Hello Emotion</div>
<script>
const app = document.getElementById('root');
const color = 'red';
const myClassName = emotion.css`
color: ${color};
`;
app.classList.add(myClassName);
</script>
</body>
</html>在 JavaScript 中使用 emotion.css 定義 CSS 樣式。