One-line: date picking — inline in a booking page, or inside a Popover as a date field.

```jsx
<Popover><PopoverTrigger><Button variant="outline"><CalendarIcon />Pick a date</Button></PopoverTrigger>
  <PopoverPopup><Calendar selected={12} onSelect={setDate} /></PopoverPopup>
</Popover>
```

Days are 32px squares on a 2px grid; the popup padding drops to 8px when it contains a Calendar.
