gecko-dev/browser/themes/shared/toolbarbutton-icons.inc.css

:root {
  --toolbarbutton-icon-fill: #4c4c4c;
  --toolbarbutton-icon-fill-inverted: #fff;
  --toolbarbutton-icon-fill-attention: #177ee5;
}

:-moz-any(@primaryToolbarButtons@) {
  -moz-context-properties: fill;
  fill: var(--toolbarbutton-icon-fill);
}

toolbar[brighttext] :-moz-any(@primaryToolbarButtons@) {
  fill: var(--toolbarbutton-icon-fill-inverted);
}

#back-button:-moz-locale-dir(rtl) > .toolbarbutton-icon,
%ifdef MOZ_PHOTON_THEME
#forward-button:-moz-locale-dir(rtl) > .toolbarbutton-icon,
#reload-button:-moz-locale-dir(rtl) > .toolbarbutton-icon,
%endif
#nav-bar-overflow-button:-moz-locale-dir(rtl) > .toolbarbutton-icon,
#panic-button:-moz-locale-dir(rtl) > .toolbarbutton-icon {
  transform: scaleX(-1);
}

#back-button {
%ifdef MOZ_PHOTON_THEME
  list-style-image: url("chrome://browser/skin/back.svg");
%else
  list-style-image: url("chrome://browser/skin/back-large.svg");
%endif
}

#forward-button {
  list-style-image: url("chrome://browser/skin/forward.svg");
}

%ifdef MOZ_PHOTON_THEME
#reload-button {
  list-style-image: url("chrome://browser/skin/reload.svg");
}

#stop-button {
  list-style-image: url("chrome://browser/skin/stop.svg");
}
%endif

#home-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/home.svg");
}

#bookmarks-menu-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/bookmark-hollow.svg");
}

#bookmarks-menu-button[cui-areatype="toolbar"][starred] {
  list-style-image: url("chrome://browser/skin/bookmark.svg");
}

toolbar:not([brighttext]) #bookmarks-menu-button[cui-areatype="toolbar"][starred] > .toolbarbutton-menubutton-button {
  -moz-context-properties: fill;
  fill: var(--toolbarbutton-icon-fill-attention);
}

#bookmarks-menu-button[cui-areatype="toolbar"] > .toolbarbutton-menubutton-dropmarker > .dropmarker-icon {
  list-style-image: url("chrome://browser/skin/bookmarksMenu.svg");
}

#history-panelmenu[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/history.svg");
}

#downloads-button[cui-areatype="toolbar"] {
%ifdef MOZ_PHOTON_THEME
  list-style-image: url("chrome://browser/skin/download-arrow-with-bar.svg");
%else
  list-style-image: url("chrome://browser/skin/download.svg");
%endif
}

#add-ons-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/addons.svg");
}

#open-file-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/open.svg");
}

#save-page-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/save.svg");
}

#sync-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/synced-tabs.svg");
}

#containers-panelmenu[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/containers.svg");
}

#feed-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/feed.svg");
}

#social-share-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/share.svg");
}

#characterencoding-button[cui-areatype="toolbar"]{
  list-style-image: url("chrome://browser/skin/characterEncoding.svg");
}

#new-window-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/new-window.svg");
}

#e10s-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/new-window.svg");
}

#e10s-button > .toolbarbutton-icon {
  transform: scaleY(-1);
}

#new-tab-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/new-tab.svg");
}

#privatebrowsing-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/privateBrowsing.svg");
}

#find-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/find.svg");
}

#print-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/print.svg");
}

%ifdef XP_MACOSX
#restore-button,
%endif
#fullscreen-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/fullscreen.svg");
}

#developer-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/developer.svg");
}

#preferences-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/settings.svg");
}

#PanelUI-menu-button {
  list-style-image: url("chrome://browser/skin/menu.svg");
}

#edit-controls:not(@inAnyPanel@) > #cut-button {
  list-style-image: url("chrome://browser/skin/edit-cut.svg");
}

#edit-controls:not(@inAnyPanel@) > #copy-button {
  list-style-image: url("chrome://browser/skin/edit-copy.svg");
}

#edit-controls:not(@inAnyPanel@) > #paste-button {
  list-style-image: url("chrome://browser/skin/edit-paste.svg");
}

#zoom-controls:not(@inAnyPanel@) > #zoom-out-button {
  list-style-image: url("chrome://browser/skin/zoom-out.svg");
}

#zoom-controls:not(@inAnyPanel@) > #zoom-in-button {
  list-style-image: url("chrome://browser/skin/zoom-in.svg");
}

#nav-bar-overflow-button {
  list-style-image: url("chrome://browser/skin/chevron.svg");
}

#email-link-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/mail.svg");
}

#sidebar-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/sidebars.svg");
}

#panic-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/forget.svg");
}

#panic-button[cui-areatype="toolbar"][open] {
  fill: rgb(213, 32, 20);
}

#webide-button[cui-areatype="toolbar"] {
  list-style-image: url("chrome://browser/skin/webIDE.svg");
}

#library-button {
  list-style-image: url("chrome://browser/skin/library.svg");
}