How to adjust color in Thunderbird menu?

Question

css

Question for those who know how to configure Mozilla via userChrome.css.
When you hover the mouse over an item in the main menu of TB, it is highlighted in a ridiculous white color - and the text is not visible. After clicking on the paragraph - changes the background to dark blue - and the text is visible again.
How to fix the color when hovering the mouse over a menu item, I found:

menu:hover {
    color: blue !important;
}

How to change menu item background color on mouse click? Like this:

menu:active {
    background-color: transparent !important;
}

does not work.

Answer 1

Screenshots.
Moved the mouse to the "Tools" item (for some reason the mouse cursor itself was not captured)
Clicked on the "Tools" item
How to remove this dark blue background?
UPD: In general, I answer to myself, as well as for the most part ...
The task of studying XUL was not there. The task was to remove the stupid background. And it was solved, but in a non-trivial way :) GTK theme, gentlemen. Yes, yes, do not believe it, changing the GTK theme via gtk-theme-switch solved all the problems. If it's MATE, then it's possible through mate-control-center, otherwise directly through gtk-theme-switch. In order to have standard GTK themes, you need to install gtk-engines - it contains several themes - Clearlooks, Mist, Industrial. And then, since the color of the menu item under the mouse becomes stupidly white - userChrome.css just helps out here.
What does the GTK theme setting affect? Even if GNOME is not used as a DE, Thunderbird, LibreOffice, Wireshark and most likely all other GTK-based programs take their settings from there