One-line: wrap every form control in a Field so label, control, help text and error share one 8px rhythm.

```jsx
<Field>
  <FieldLabel htmlFor="slug">Event URL</FieldLabel>
  <Input id="slug" defaultValue="30min" />
  <FieldDescription>Lowercase letters, numbers and dashes.</FieldDescription>
</Field>
```

Show \`FieldError\` instead of \`FieldDescription\` when the control is invalid — never both.
