One-line: reserve the shape of content that is still loading — match the real element's size, do not shrink it.

```jsx
<div className="o-stack"><Skeleton style={{height:16,width:"60%"}} /><Skeleton style={{height:16,width:"40%"}} /></div>
```

The sheen is a 120° gradient sweeping a fixed background — it reads as one light passing across a whole group, not per-block.
