[vinayagg]

Conversation replies stretched across wide panes, with heavy message backgrounds and crowded composer controls on small screens. This updates the shared desktop, browser and phone stylesheet with a comfortable message width, quieter sidebar, clearer tabs, a distinct composer, larger touch targets and contained table scrolling. Existing themes and interactions are preserved.

Validation:

• npm run check passed, including both client builds.
• Browser checks passed for light/dark themes, widths 320–1440, split panels, long titles/code/tables, keyboard tab navigation, draft retention, search, empty threads, visible focus and reduced motion.
• Visual review used sample data; the native desktop app and physical phones were not tested.