## zh-CN

最简单的用法。

## en-US

The most basic usage.

```css
.site-back-top-basic {
  color: rgba(64, 64, 64, 0.6);
}
```

<style>
[data-theme="dark"] .site-back-top-basic {
  color: rgba(255,255,255,.45);
}
</style>
