fix: Enhance Cube Manager mobile UI by adjusting sidebar and header layouts and disabling card hover previews.

docs/development/devlog/2025-12-17-005000_mobile_ui_fixes.md

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+# Cube Manager Mobile Improvements
+
+## Objective
+Fix usability issues on mobile devices where UI elements were overlapping and "unusable".
+
+## Changes
+1.  **Sidebar Responsiveness**:
+    -   Modified `CubeManager.tsx` to apply `sticky` positioning to the left sidebar *only* on large screens (`lg:` prefix). On mobile, it is now standard static flow.
+    -   Limited `max-height` and `overflow-y-auto` only to `lg:` screens.
+
+2.  **Header Improvements**:
+    -   Updated the "Packs" sticky header in `CubeManager.tsx` to handle wrapping gracefully.
+    -   Added `backdrop-blur-xl` and slightly higher opacity to ensure content behind it doesn't bleed through visually (fixing "overlap" perception).
+    -   Enabled `overflow-x-auto` for the buttons container to prevent them from breaking out of the viewport on very narrow screens.
+
+3.  **Disable Heavy Hovers**:
+    -   Modified `CardPreview.tsx` to disable the `FloatingPreview` (large full-card hover) on devices with width < 1024px. This prevents the preview from sticking or covering the UI on touch devices.
+
+## Result
+The UI should now be clean and usable on mobile, with no overlapping elements and a natural scroll flow.