Method for stylizing the context menu (Firefox CSS)

userChrome.css

/* ----------------------------------------------------------
Styling Firefoxs context (right-click) menu
- this will target all context menus, including the menubar, and drop downs.
- If you want this to only apply to the context menu activated within webpages you can specify it, such as: #contentAreaContextMenu
-----------------------------------------------------------*/

/*
Using your own defined variables makes switching styles/colors much easier to manage
*/

:root, body, * {
  
--uc-background-color: rgba(28, 27, 34,1);
--uc-border-color: rgba(28, 27, 34,0.5);
--uc-text-color: rgb(255, 255, 255);
--uc-border-radius: 10px;
--uc-selected: rgba(0,0,0,1);
--uc-hover: rgba(0,0,0,0.7);
}

/*
Example of removing context menu items below;
Refer to SMW for an all in one place reference-library: https://github.com/stonecrusher/simpleMenuWizard
*/

#context-take-screenshot
#context-sep-screenshots,
#context-sendimage,
#context-setDesktopBackground,
#context-sep-setbackground,
#context-openlinkinusercontext-menu
    {
        display: none !important;
    }

#context-pocket,
#context-savelinktopocket,
#tabContextMenu #context_duplicateTab,         
#tabContextMenu #context_duplicateTabs,
#tabContextMenu #context_bookmarkSelectedTabs
    {
        display: none !important;
    }

/*
Apply your variables, style, color, etc, to the context menu
*/

menupopup, panel {
  color-scheme: light dark;
  --panel-background: var(--uc-background-color) !important;
  --panel-color: var(--uc-text-color) !important;
  --panel-border-radius: var(--uc-border-radius) !important;
  --panel-border-color: var(--uc-border-color) !important;
  --panel-shadow: 0 0 var(---uc-border-color) hsla(0,0%,0%,.2); 
}

menuitem:hover{
  background-color: var(--uc-hover) !important;
  color: var(--uc-text-color) !important;
 }

menu:where([_moz-menuactive="true"]:not([disabled="true"])),
menuitem:where([_moz-menuactive="true"]:not([disabled="true"])){
  background-color: var(--uc-selected) !important;
  color: var(--uc-text-color) !important;
}

This is it on Windows, with different color for light mode. You can have it auto adjust to light/dark mode as well with media queries. See FF ULTIMA for an example