fix: improve mobile menu performance and TOC visibility (#265)

* fix: improve mobile menu performance and TOC visibility

- Speed up offcanvas animation from 0.3s to 0.15s for better responsiveness
- Fix excessive whitespace above content on mobile devices
- Fix TOC content not showing by updating selector for new offcanvas structure
- Hide mobile control buttons when offcanvas is shown to prevent overlap

These changes provide a smoother mobile experience with faster menu
transitions and proper content visibility.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

* fix: address Gemini code review feedback

- Fix JavaScript variable redeclaration error that prevented auto-close functionality
- Remove \!important from CSS using more specific selector for better maintainability
- Clean up redundant CSS selector fallbacks

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

* feat: implement Bootstrap 5.3 best practices and dark theme

- Add full dark theme support with theme switcher in navbar
- Update all colors to use CSS variables for proper theme switching
- Fix navigation layout issues on mobile devices
- Use Bootstrap vertical nav pills for sidebar navigation
- Update navbar to follow Bootstrap 5.3 patterns
- Align breakpoints with Bootstrap 5.3 standards (md: 768px)
- Add proper ARIA labels for better accessibility
- Implement focus-visible styles for keyboard navigation
- Add smooth transitions for theme switching
- Use consistent button sizing (btn-sm) throughout
- Add gutter-0 to main row for proper spacing
- Convert navigation toggle from anchor to button element
- Add role attributes for semantic HTML

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

* fix: resolve responsive layout issues and TOC positioning

- Fix desktop sidebar visibility by implementing proper responsive offcanvas classes
- Add offcanvas-md and offcanvas-lg for proper breakpoint behavior
- Fix TOC column layout to only show on large screens (≥992px)
- Resolve "On this page" heading positioning in TOC sidebar
- Add explicit flex-direction and width constraints for proper vertical stacking
- Update column widths to prevent layout overflow on medium screens
- Ensure TOC content displays below header instead of alongside it

Layout behavior:
- Large screens (≥992px): All three columns visible (sidebar, content, TOC)
- Medium screens (768px-991px): Sidebar and content visible, TOC as offcanvas
- Small screens (<768px): Only content visible, both sidebars as offcanvas

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

* fix: hide non-functional TOC button on mobile screens

- Hide "On this page" button on mobile (<768px) where TOC offcanvas doesn't work properly
- Keep TOC button visible only on medium screens (768px-991px) where it functions correctly
- Remove debug console logging statements
- Improve mobile UX by eliminating confusing non-functional UI elements

Button visibility:
- Mobile (<768px): Hidden - cleaner mobile experience
- Medium (768px-991px): Visible - TOC works as offcanvas
- Large (≥992px): Hidden - TOC visible as sidebar

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

---------

Co-authored-by: Claude <[email protected]>

Author: pekkah

test-build/HEAD/01-getting-started/configuration.html

@@ -0,0 +1,5 @@
+id: getting-started
+title: "Getting Started"
+index_page: xref://getting-started:getting-started.md
+nav:
+  - xref://nav.md 

test-build/HEAD/01-getting-started/getting-started.html

@@ -0,0 +1,5 @@
+id: project-structure
+title: "Project Structure"
+index_page: xref://project-structure:index.md
+nav:
+  - xref://nav.md