[Bug]: Navbar logo and text collapse on theme toggle

Hi,mentors- @ashley-cui @TomSweeneyRedHat
When toggling between light and dark theme, the navbar logo and "podman" text briefly collapse/shrink, appearing unstable. The image and text momentarily misalign before settling.
### Steps to reproduce
1. Go to podman.io
2. Click the theme toggle button (light/dark)
3. Observe the navbar logo and text
4. Repeat multiple times

->Expected behavior -Logo and text should remain stable and properly aligned when toggling theme — no collapse, shrinking, or layout shift.

->Actual behavior - Logo container loses explicit width during re-render - "podman" text collapses into logo space Layout momentarily breaks before correcting .

->Root cause -The `.navbar__logo` container has only `height` but no explicit `width` constraint. During theme toggle, the brief re-render causes the image to lose its computed width, triggering the collapse. The `img` element inside also lacks fixed dimensions.

Environment - Browser: Chrome, Safari, Firefox (all affected) - Device: Desktop and mobile

### Upload screenshots or screen recordings

## Before fix (bug visible)

https://github.com/user-attachments/assets/04765d12-fe43-4e9b-95bd-94fb7c674c67

## After fix (stable)

https://github.com/user-attachments/assets/fc95a0dc-3e20-43ff-ba32-3d37cfcc91dd

### LLM Policy

- [x] This issue is human-written, and folow up comments will also be human-written

Search the navbar implementation for the `.navbar__logo` selector and the theme toggle entry point, then inspect how the logo image and text are sized during theme changes. Reproduce the toggle in Chrome, Safari, or Firefox; done means the logo and “podman” text stay aligned without shrinking or layout shift.

Written by the indexing model from the issue text.