userChrome.css

@media (prefers-color-scheme: dark) {
  :root {
    --zen-colors-primary: #1e1e2e !important;
    --zen-primary-color: #cba6f7 !important;
    --zen-colors-secondary: #313244 !important;
    --zen-colors-tertiary: #181825 !important;
    --zen-colors-border: #313244 !important;
    --toolbarbutton-icon-fill: #cdd6f4 !important;
    --lwt-text-color: #cdd6f4 !important;
    --toolbar-field-color: #cdd6f4 !important;
    --tab-selected-textcolor: rgb(193, 200, 246) !important;
    --toolbar-field-focus-color: #cdd6f4 !important;
    --toolbar-color: #cdd6f4 !important;
    --newtab-text-primary-color: #cdd6f4 !important;
    --arrowpanel-color: #cdd6f4 !important;
    --arrowpanel-background: #1e1e2e !important;
    --sidebar-text-color: #cdd6f4 !important;
    --lwt-sidebar-text-color: #cdd6f4 !important;
    --lwt-sidebar-background-color: #181825 !important;
    --toolbar-bgcolor: #313244 !important;
    --newtab-background-color: #1e1e2e !important;
    --zen-themed-toolbar-bg: #181825 !important;
    --zen-main-browser-background: #181825 !important;
    --newtab-primary-action-background: #cba6f7 !important;
    --toolbox-bgcolor-inactive: #181825 !important;
  }

  #zen-workspaces-button {
    background-color: #1e1e2e !important;
  }

  #urlbar-background {
    background-color: #181825 !important;
  }

  .content-shortcuts {
    background-color: #1e1e2e !important;
    border-color: #cba6f7 !important;
  }

  .urlbarView-url {
    color: #cba6f7 !important;
  }

  .urlbar-input-box {
    text-align: center;
  }

  #zenEditBookmarkPanelFaviconContainer {
    background: #181825 !important;
  }
}

#zen-essentials-container {
  margin-bottom: 3px !important;
}

#zen-current-workspace-indicator-container {
  display: none !important;
}