[Lin] minimize, maximize and close buttons inaccessible or invisible with the titlebar and menubar disabled

[hal9000jw]

1. Does the issue occur without any files inside /chrome/ folder?
   No

2. Issue description:
   enabling import "./css/tabs/tabs_below_navigation_toolbar.css"; /**/ in userChrome.css results in the minimize, maximize and close buttons being inaccessible or invisible with the titlebar and menubar disabled. A workaround is to enable either the titlebar or the menubar.

3. Does the issue occur with the most recent version of CustomCSSforFx (release/test/dev build)?
   Yes, testing CustomCSSforFx 4.6.9

4. Screenshots showing the issue:
   
   

5. System information:

• OS & OS version: Linux Mint 20.3
• DPI/HiDPI/scaling value: 100%
• Firefox version: 134.0.2 (64-bit)
• Firefox theme: Happens with both Dark 1.3.2 and https://addons.mozilla.org/en-US/firefox/addon/in-the-end/
• Is 'about:config > toolkit.legacyUserProfileCustomizations.stylesheets' set to 'true': Yes

[Aris-t2]

Hi, I could run some test on Linux with Firefox 134.0.2 today.

• Firefox titlebar
• menubar hidden
• maximized mode
• normal mode

I have tested (dark) themes on browsers/project vanilla setup with only tabs_below_navigation_toolbar.css enabled. Caption buttons appeared correctly.

[hal9000jw]

@Aris-t2 Would you retest with the firefox titlebar disabled? With the titlebar enabled, I also confirmed that the caption buttons were functional in initial testing.

[D3SL]

I can reproduce this on Windows 10 with v4.7.0 and firefox 135. If I enable ./css/tabs/tabs_below_navigation_toolbar.css and disable "./css/tabs/classic_squared_tabs.css"; the minimize/close/window buttons disappear. It seems classic squared and photon tabs are compatible with tabs not on top but the default tabs are not.

Tab colors also seem to be misbehaving and not following any kind of logical responsiveness, which may be tied to this.

[hal9000jw]

I also have ./css/tabs/classic_squared_tabs.css disabled, but I wouldn't have guessed that it was related to the issue.

[lucianlau]

As a workaround I have found you can enable Firefox titlebar as @Aris-t2 has or enable Menu bar

In my particular setup I only have ./css/appbutton/appbutton_on_navbar_color_autocolor.css and ./css/tabs/tabs_below_navigation_toolbar.css enabled. I have also edited appbutton_on_navbar_color_autocolor so it only appears on private tabs but I don't think that influences this particular issue.

[Aris-t2]

This missing code from tabs_below_navigation_toolbar.css was causing the issue.

#nav-bar:not([tabs-hidden="true"]) {
  position: unset !important;
}

[Aris-t2]

I have added this to current 4.7.5 release.