Firefox userChrome

userChrome.css

/*
 * Open profile folder from about:support
 * Place userChrome.css in [profile folder]/chrome/userChrome.css
 */
@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);

/* Shorten the height of tabs in the tab bar: */
.tabbrowser-tab {
  --tab-min-height: 2.8rem !important;
}

/* Remove all bookmarks bar icons, add a disclosure triangle for folders (Safari-fy): */
#personal-bookmarks .bookmark-item .toolbarbutton-icon,
#personal-bookmarks .bookmark-item .menu-iconic-left {
  display: none !important;
}

#personal-bookmarks .bookmark-item .menu-iconic-text {
  padding-inline-start: 0 !important;
}

#PlacesToolbarItems .bookmark-item[container="true"]::after {
  content: url("chrome://global/skin/icons/arrow-down-12.svg");
  margin-inline-start: .25em;
  display: inherit;
}