my firefox userChrome.css file (check about:profiles), and config

userChrome.css

/*
 MAKE SURE toolkit.legacyUserProfileCustomizations.stylesheets IS SET TO TRUE!
 Also set:
 * mousewheel.with_meta.action	= 3 // When cmd+scroll to zoom is used (macOS)
 * mousewheel.with_control.action = 3 // When ctrl+scroll to zoom (!macOS).
 * privacy.resistFingerprinting = true
 * privacy.resistFingerprinting.autoDeclineNoUserInputCanvasPrompts = false
 * privacy.userContext.enabled = false // disables 'open in new container tab'
 And turn titlebar on in the "customize toolbar" page.
*/

/* Hide horizontal tabs at the top of the window
   From https://github.com/piroor/treestyletab/wiki/Code-snippets-for-custom-style-rules#hide-horizontal-tabs-at-the-top-of-the-window-1349-1672-2147
*/
#main-window[tabsintitlebar="true"]:not([extradragspace="true"]) #TabsToolbar > .toolbar-items {
  opacity: 0;
  pointer-events: none;
}
#main-window:not([tabsintitlebar="true"]) #TabsToolbar {
    visibility: collapse !important;
}

toolbarbutton.bookmark-item
{
 font-size:15px !important;
}