tabsAsHeaderbar: Fitt's law - hard to click tabs when maxmized

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Describe the bug

As a Firefox user, I often switch tabs on a maximized window by flinging my mouse cursor to the top of the screen and then clicking. By changing gnomeTheme.tabsAsHeaderbar to true, I expect this behaviour to be consistent with standard Firefox; however, it drags the window around instead.

To Reproduce

1. Have the following settings set to:
   • gnomeTheme.tabsAsHeaderbar: true
2. On a secondary screen (without the GNOME top bar), try to switch tabs while Firefox is maximized, while the cursor is at the top edge of the screen
3. Notice that the click target for the tabs does not extend to the edge of the screen

Expected behavior

The click target for each tab extends to the top edge of the screen, i.e., I can switch tabs by flinging my cursor to the top of the screen and then clicking.

Screenshots

Setup information

• OS: Fedora 39
• Installation method: mozilla-flatpak - 1.0
• Firefox version: 121.0
• Theme version: Commit 7a1a81baa7c31d75764dcea908285e487302d32a
• Optional features enabled: gnomeTheme.tabsAsHeaderbar

Additional context

The following CSS in customChrome fixes the issue however it messes up the positioning of the tabs:

:root[tabsintitlebar] #titlebar .titlebar-buttonbox-container {
    padding: 0 !important;
}