mobile-config-firefox/chrome/linux_gtk_window_control_patch.css

/* Source file https://github.com/MrOtherGuy/firefox-csshacks/tree/master/chrome/linux_gtk_window_control_patch.css made available under Mozilla Public License v. 2.0
See the above repository for updates as well as full license text. */

/* Overrides the appearance of the window controls with something that more closely matches "normal" buttons*/
/* More importantly, this makes window controls to respect layout rules the other styles rely on */

.titlebar-buttonbox{
  -moz-box-align: stretch !important; /* Fx <112 compatibility */
  align-items: stretch !important;
}
.titlebar-button {
  -moz-appearance: none !important;
  -moz-context-properties: fill, stroke, fill-opacity;
  fill: currentColor;
  padding: 4px 6px !important;
  -moz-box-flex: 1;
  flex-grow: 1;
  overflow: -moz-hidden-unscrollable;
}
.titlebar-button:hover{ background-color: rgba(0,0,0,0.1) }
.titlebar-min{ list-style-image: url(chrome://browser/skin/zoom-out.svg); }
.titlebar-close{
  list-style-image: url(chrome://global/skin/icons/close.svg);
  fill-opacity: 0;
  stroke: currentColor
}