# Description of Changes
This PR fixes responsiveness issues with the multi-tool interface when
zooming/narrowing the screen, implementing a zoom-responsive sidebar and
resolving navbar scaling conflicts.
## What was changed
• **Zoom-Responsive Sidebar**: Converts horizontal bottom buttons to
vertical left sidebar at 175%+ zoom using CSS media queries.
• **Fixed Navbar Scaling Bug**: Prevents desktop zoom from triggering 3x
mobile navbar scaling by requiring actual mobile device detection.
• **DPR Detection**: Uses Device Pixel Ratio to distinguish window
narrowing (3rem buttons) vs browser zoom (2.5rem buttons)
## Why the change was made
- **Accessibility**: Users zooming for accessibility reasons were
getting poor UX with bottom floating buttons
- **Bug Fix**: Desktop zoom was incorrectly triggering mobile navbar
scaling (3x size), making the interface unusable
- **Multi-context Support**: Different users narrow windows for
split-screen work vs zoom for accessibility - each needs different icon
sizes
## Checklist
### General
- [x] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [x] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [x] I have performed a self-review of my own code
- [x] My changes generate no new warnings
### Documentation
- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)
### UI Changes (if applicable)
- [x] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)
### Testing (if applicable)
- [x] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.