[Bug] [bug-bash] Side Nav (+ Collapse Button, Item, Section): Overview preview appears top-aligned (not how component is built)

### Description

On the **Overview** tab preview, the component appears **aligned to the top** of the preview area, even though it isn't built that way. The preview container seems to be top-aligning the component rather than centering/sizing it as intended.

Affects the same family of components:

- Side Nav — https://xds-sandbox.vercel.app/components/SideNav
- Side Nav Collapse Button
- Side Nav Item
- Side Nav Section

### Reproduction

1. Open https://xds-sandbox.vercel.app/components/SideNav
2. Stay on the **Overview** tab
3. The component renders top-aligned in the preview box (not how it's actually built)
4. Same behavior on Side Nav Collapse Button, Side Nav Item, and Side Nav Section

### Expected

The Overview preview should display these components with correct alignment, matching how they're actually built.