fix(ui): show horizontal scrollbar on code blocks in markdown

[haliliceylan]

Context

fixes #406

closes #406

Code blocks displayed in chat sessions had no visible horizontal scrollbars, making it impossible to scroll horizontally to view long lines of code except by highlighting and dragging.

Implementation

Modified packages/ui/src/components/markdown.css to show horizontal scrollbars on pre elements:

• Changed scrollbar-width: none to scrollbar-width: thin for Firefox
• Added scrollbar-color for Firefox styling using design system variables
• Updated webkit scrollbar styling to show horizontal scrollbar (height: 8px) while hiding vertical scrollbar (width: 0)
• Styled scrollbar thumb with design system colors (--border-weak-base, --border-strong-base on hover)

Screenshots

before	after
please see #406

How to Test

Trigger a response that includes a code block with long lines

Get in Touch

https://discord.com/channels/1349288496988160052/1391109167275577464/1473821631267995872

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[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

See CONTRIBUTING.md for details.

[kiloconnect]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

This PR improves scrollbar styling across the UI:

• Hides scrollbar arrow buttons globally and in the VS Code theme by changing display: block → display: none with width: 0
• Adds custom thin scrollbar styling for pre elements in the markdown component with both standard (scrollbar-width, scrollbar-color) and WebKit-specific pseudo-elements for cross-browser support
• Updates flake.lock (nixpkgs version bump)

Files Reviewed (3 files)

• flake.lock - lock file update (skipped)
• packages/kilo-ui/src/components/markdown.css - no issues
• packages/kilo-ui/src/styles/globals.css - no issues