Title: Sections view layout breaks (overlapping/misaligned cards) at narrow viewport widths since 2026.8.x

[titi294]

Environment:

Home Assistant Core: 2026.8.2 (regression from 2026.3.0, which worked fine)
Reproduced on: desktop browser (Chrome), Android Companion App, Fully Kiosk Browser — all affected equally at narrow widths
Not reproduced on: wide desktop/laptop browser windows

Description:
Dashboard using type: sections view with multiple cards using grid_options (columns/rows). Layout renders correctly on wide viewports (desktop/laptop) but breaks on narrower viewports (10" and 14" Android tablets) — cards overlap, get cut off, or leave large empty gaps. Cameras inside vertical-stack cards and cards with grid_options.columns values >12 seemed like likely culprits and were corrected, but the issue persists regardless.

Steps to reproduce:

Build a sections dashboard with several cards using grid_options (mixed columns/rows, including custom cards like button-card, vertical-stack with picture-entity cameras).
View on a wide desktop browser window — layout is correct.
View the same dashboard at a narrower viewport (e.g. via Chrome DevTools responsive mode at ~1200px width or less, or on a tablet) — cards misalign, overlap, or show incorrect heights.

Expected: Layout should reflow cleanly and consistently at any viewport width, matching desktop rendering.

Actual: Cards overlap/misalign below a certain width threshold, reproducible across different browser engines (rules out browser-specific cache/WebView issue).

Workaround: Downgraded to 2026.3.0 while waiting for a fix.