Searchbar label colours/background problem

### Guidelines

- [x] I have read [how to report a new issue](https://github.com/Aris-t2/CustomCSSforFx/issues/4)
- [x] I have used the [latest release](https://github.com/Aris-t2/CustomCSSforFx/releases/latest)
- [x] I have set the `toolkit.legacyUserProfileCustomizations.stylesheets` in `about:config` to `true`

### Does the issue occur without any files inside /chrome/ folder?

No

### Description of the Issue

Searbar background seems to be the same gray colour as the font (despite using dark theme), and I cannot locate how to control it.

### Issue description, userChrome.css/userContent.css 'settings' the issue occurs with and steps to reproduce the issue

I cannot find a reason why labels on macOS the searchbar became unreadable, it happened after one of FF releases (unsure which one).

And I could not find an option in config that would fix it, it looks like an issue beyond my skills.

My [chrome.zip](https://github.com/user-attachments/files/25112487/chrome.zip) attached.

### Does the issue occur with the most recent version of CustomCSSforFx (release/test/dev build)?

Yes, with the latest release

### Screenshots showing the issue

It looks like this (text labels the same colour like background)

### System information

- OS & OS version: macOS 26.2
- DPI/HiDPI/scaling value, if not 100% (e.g. 125%, 150%...):
- Firefox version: 147.0.3
- Firefox theme (e.g. default, build in light/dark, external theme + link): built in dark

Start by unpacking the attached chrome.zip and reviewing the userChrome.css and userContent.css files that affect the searchbar, then reproduce the unreadable labels in Firefox 147.0.3 on macOS with the built-in dark theme. Done means the searchbar labels and background have visibly distinct, readable colours without breaking the reported customization.

Written by the indexing model from the issue text.