文章详细介绍了如何为“电车充电券规划计算器”创建和配置 `manifest.json`、`service-worker.js` 并更新 `index.html`，以实现离线访问和优化用户体验。
G18: Ensuring that a contrast ratio of at least 4.5:1 exists between text (and images of text) and background behind the text
到底是怎么写出来的呢？