[Bug] Mobile layout broken: sidebar expanded view is cramped/overlapping

[nevergow]

Environment

• dsh v0.1.0-rc.5 (developer preview, source build)
• iPhone (iOS 26.5.2), Edge browser, Web UI over HTTPS (LAN)

Bug

On mobile, after expanding the sidebar, many elements are cramped and overlapping (排版很乱、很挤). The layout does not adapt to narrow viewports.

Expected

Responsive layout that renders cleanly on mobile when the sidebar is expanded.

Repro

1. Open dsh web UI on a phone
2. Expand the sidebar
3. Observe cramped/overlapping elements

Screenshots available on request.