firefox-gnome-theme/theme/parts/buttons.css

/* Buttons */

@namespace xul "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";

/* Hide buttons separator */
#nav-bar .toolbaritem-combined-buttons separator {
	display: none !important;
}
#appMenu-popup .toolbaritem-combined-buttons toolbarseparator {
	border: 0 !important;
}

/* Buttons */
menulist,
#nav-bar toolbarbutton:not(#urlbar-zoom-button):not(.subviewbutton),
.subviewbutton.panel-subview-footer,
.panel-footer button,
#downloadsPanel-mainView .download-state .downloadButton,
#appMenu-popup .panel-banner-item,
#appMenu-popup .toolbaritem-combined-buttons toolbarbutton:not(#appMenu-fxa-label),
#context-navigation menuitem,
.identity-popup-preferences-button:not(#hack),
.findbar-container toolbarbutton,
#sidebar-switcher-target,
#viewButton,
.close-icon:not(.tab-close-button),
button.close,
.menulist-label-box,
.expander-down, .expander-up,
.notification-button,
#identity-popup-security-expander,
#protections-popup-info-button,
#PanelUI-panic-view-button,
.tracking-protection-button,
.dialog-button,
.autocomplete-richlistitem[type="loginsFooter"],
.dialog-button-box button,
.searchbar-engine-one-off-item,
.permission-popup-permission-remove-button,
.button.connect-device,
#item-choose button,
#editBMPanel_newFolderButton {
	-moz-appearance: none !important;
	background: var(--gnome-button-background) !important;
	border-radius: 6px !important;
	border: 0 !important;
	padding: 0 1px !important;
	height: 34px !important;
	max-height: 34px !important;
	min-height: 34px !important;
	min-width: 34px !important;
	color: var(--gnome-toolbar-color) !important;
	outline: 0 !important;
	font: menu !important;
	-moz-box-align: center !important;
	transition: 0.3s;
}
.subviewbutton-iconic {
	-moz-box-pack: center !important;
}

/* Flat Buttons */
#nav-bar toolbarbutton:not(#urlbar-zoom-button):not(.subviewbutton),
.close-icon:not(.tab-close-button),
button.close,
#protections-popup-info-button,
.permission-popup-permission-remove-button {
	background: transparent !important;
	transition: 0.3s;
}

/* Buttons with margins */
#nav-bar toolbarbutton:not(#urlbar-zoom-button):not(.subviewbutton),
.notification-button,
.subviewbutton.panel-subview-footer:not(:only-of-type),
.panel-footer button:not(:only-of-type) {
	margin: 0 3px !important;
}
.close-icon:not(.tab-close-button) {
	margin-left: 6px !important;
}

/* Text buttons */
menulist,
.subviewbutton.panel-subview-footer,
.panel-footer button,
#appMenu-popup .panel-banner-item,
#appMenu-popup #appMenu-zoomReset-button2:not(#hack),
#tracking-protection-preferences-button:not(#hack),
.findbar-container toolbarbutton.findbar-button,
.notification-button,
#PanelUI-panic-view-button,
.tracking-protection-button,
.dialog-button,
.autocomplete-richlistitem[type="loginsFooter"],
.dialog-button-box button,
.toolbaritem-combined-buttons:is(:not([cui-areatype="toolbar"]), [overflowedItem="true"]) > #appMenu-fxa-label2:not(#hack),
.button.connect-device,
#item-choose button,
#editBMPanel_newFolderButton {
	padding: 2px 16px !important;
}
.subviewbutton.panel-subview-footer label,
.panel-footer button,
#appMenu-popup .panel-banner-item .toolbarbutton-text,
#appMenu-popup #appMenu-zoomReset-button2:not(#hack),
#tracking-protection-preferences-button:not(#hack),
.findbar-container toolbarbutton.findbar-button,
.notification-button,
#PanelUI-panic-view-button,
.tracking-protection-button,
.dialog-button,
.autocomplete-richlistitem[type="loginsFooter"],
.dialog-button-box button,
.button.connect-device,
#item-choose button {
	text-align: center !important;
}

/* Drop down buttons */
#sidebar-switcher-target,
#viewButton {
	padding: 2px 16px !important;
	position: relative;
}
#sidebar-switcher-arrow,
#viewButton .button-menu-dropmarker { /* Arrow position, type b */
	transform: translate(6px, 0)
}
.menulist-label-box {
	padding: 2px 26px 2px 16px !important;
	position: relative;
}
.menulist-label-box:after { /* Arrow position */
	position: absolute !important;
	right: 8px !important;
	top: 8px !important;
}
.menulist-label-box:after { /* Create arrow if icon tag no exist */
	content: "";
}

/* Hover buttons */
menulist:hover,
.subviewbutton.panel-subview-footer:hover,
.panel-footer button:hover,
#downloadsPanel-mainView .download-state .downloadButton:hover,
#appMenu-popup .panel-banner-item:hover,
#appMenu-popup .toolbaritem-combined-buttons toolbarbutton:not(#appMenu-fxa-label):not([disabled="true"]):hover,
#context-navigation menuitem:not([disabled="true"]):hover,
.identity-popup-preferences-button:not(#hack):hover,
.findbar-container toolbarbutton:hover,
.findbar-closebutton .toolbarbutton-icon:hover,
#sidebar-switcher-target:hover,
#viewButton:hover,
menulist:hover .menulist-label-box,
.expander-down:hover, .expander-up:hover,
.notification-button:hover,
#identity-popup-security-expander:hover,
.tracking-protection-button:hover,
.dialog-button:hover,
.autocomplete-richlistitem[type="loginsFooter"]:hover,
.dialog-button-box button:not([disabled="true"]):hover,
.searchbar-engine-one-off-item:hover,
.button.connect-device:hover,
#editBMPanel_newFolderButton:hover {
	outline: 0 !important;
	background: var(--gnome-button-hover-background) !important;
}

/* Hover flat buttons */
#nav-bar toolbarbutton:not(#urlbar-zoom-button):not(.subviewbutton):not([open]):not([disabled="true"]):not([checked]):hover,
.close-icon:not(.tab-close-button):hover,
button.close:hover,
#protections-popup-info-button:hover,
.permission-popup-permission-remove-button:hover,
#item-choose button:hover {
	outline: 0 !important;
	background: var(--gnome-button-flat-hover-background) !important;
}

/* Active buttons */
menulist[open],
.subviewbutton.panel-subview-footer:active,
.panel-footer button:active,
#downloadsPanel-mainView .download-state .downloadButton:active,
#appMenu-popup .panel-banner-item:active,
#appMenu-popup .toolbaritem-combined-buttons toolbarbutton:not([disabled="true"]):not(#appMenu-fxa-label):active,
#context-navigation menuitem:active:not([disabled="true"]),
.identity-popup-preferences-button:not(#hack):active,
.findbar-container toolbarbutton[checked],
.findbar-container toolbarbutton:active,
#sidebar-switcher-target:active, #sidebar-switcher-target.active,
#viewButton[open],
menulist[open] .menulist-label-box,
.expander-down:active, .expander-up:active,
.notification-button:active,
#identity-popup-security-expander:active,
.tracking-protection-button:active,
.dialog-button:active,
.autocomplete-richlistitem[type="loginsFooter"]:active,
.dialog-button-box button:not([disabled="true"]):active,
.button.connect-device:active,
#editBMPanel_newFolderButton:active {
	background: var(--gnome-button-active-background) !important;
}

/* Active flat buttons */
#nav-bar toolbarbutton:not(#urlbar-zoom-button):not(.subviewbutton):not([disabled="true"]):not(#hack):active,
#nav-bar toolbarbutton:not(#urlbar-zoom-button):not(.subviewbutton):not(.subviewbutton):not([disabled="true"])[open],
#nav-bar toolbarbutton:not(#urlbar-zoom-button):not(.subviewbutton):not([disabled="true"])[checked],
.close-icon:not(.tab-close-button):active,
button.close:active,
#protections-popup-info-button:not(#hack):active,
#protections-popup-info-button:not(#hack)[checked],
.permission-popup-permission-remove-button:active,
#item-choose button:active {
	background: var(--gnome-button-flat-active-background) !important;
}

/* Disabled buttons */
#nav-bar toolbarbutton:not(#urlbar-zoom-button)[disabled="true"],
#appMenu-popup .toolbaritem-combined-buttons toolbarbutton[disabled="true"],
#context-navigation menuitem[disabled="true"],
.dialog-button-box button[disabled="true"] {
	opacity: .5 !important;
}

/* Inactive window buttons */
#nav-bar toolbarbutton:not(#urlbar-zoom-button):not(.subviewbutton):-moz-window-inactive,
.findbar-container toolbarbutton:-moz-window-inactive,
#sidebar-switcher-target:-moz-window-inactive,
#viewButton:-moz-window-inactive,
.notification-button:-moz-window-inactive {
	background: var(--gnome-inactive-button-background) !important;
	box-shadow: var(--gnome-inactive-button-box-shadow) !important;
	border-color: var(--gnome-inactive-button-border-color) !important;
}

/* Circle buttons */
#downloadsPanel-mainView .download-state .downloadButton,
.permission-popup-permission-remove-button:not(#hack) {
	border-radius: 100% !important;
}

/* Combined buttons */
#nav-bar .toolbaritem-combined-buttons:not(.unified-extensions-item) toolbarbutton:not(:last-of-type):not(#hack),
#appMenu-popup .toolbaritem-combined-buttons:not(.unified-extensions-item) toolbarbutton:not(:last-of-type):not(#appMenu-zoomEnlarge-button),
#context-navigation menuitem:not(:last-of-type),
.findbar-container toolbarbutton.findbar-find-previous,
.findbar-button:not(:last-of-type),
.search-panel-one-offs .searchbar-engine-one-off-item:not(:last-child) {
	border-top-right-radius: 0 !important;
	border-bottom-right-radius: 0 !important;
	border-right-width: 0 !important;
	margin-right: 0 !important;
}

#nav-bar .toolbaritem-combined-buttons:not(.unified-extensions-item) toolbarbutton:not(:first-of-type):not(#hack),
#appMenu-popup .toolbaritem-combined-buttons:not(.unified-extensions-item) toolbarbutton:not(:first-of-type):not(#appMenu-fullscreen-button),
#context-navigation menuitem:not(:first-of-type),
.findbar-container toolbarbutton.findbar-find-previous,
.findbar-container toolbarbutton.findbar-find-next,
.findbar-button:not(:first-of-type),
.search-panel-one-offs .searchbar-engine-one-off-item:not(:first-child) {
	border-top-left-radius: 0 !important;
	border-bottom-left-radius: 0 !important;
	margin-left: 0 !important;
}

#nav-bar .toolbaritem-combined-buttons:not(.unified-extensions-item) {
	margin-left: 0 !important;
	margin-right: 0 !important;
}

/* Opaque buttons */
#appMenu-popup .panel-banner-item[notificationid="update-restart"],
button.popup-notification-primary-button,
#editBookmarkPanelDoneButton,
#tracking-action-block,
.button.connect-device,
#editBookmarkPanelRemoveButton,
#PanelUI-panic-view-button {
	color: white !important;
	font-weight: bold !important;
}

/* Buttons with suggested action */
#appMenu-popup .panel-banner-item[notificationid="update-restart"],
button.popup-notification-primary-button:not(#hack),
#editBookmarkPanelDoneButton,
#tracking-action-block,
.button.connect-device {
	background-color: var(--gnome-button-suggested-action-background) !important;
}

/* Buttons with destructive action */
#editBookmarkPanelRemoveButton,
#PanelUI-panic-view-button {
	background-color: var(--gnome-button-destructive-action-background) !important;
}

/* Opaque buttons hover */
#appMenu-popup .panel-banner-item[notificationid="update-restart"]:hover,
button.popup-notification-primary-button:hover,
#editBookmarkPanelDoneButton:hover,
#tracking-action-block:hover,
.button.connect-device:hover,
#editBookmarkPanelRemoveButton:hover,
#PanelUI-panic-view-button:hover {
	background-image: linear-gradient(rgba(255, 255, 255, .1), rgba(255, 255, 255, .1)) !important;
}

/* Opaque buttons active */
#appMenu-popup .panel-banner-item[notificationid="update-restart"]:active,
button.popup-notification-primary-button:active,
#editBookmarkPanelDoneButton:active,
#tracking-action-block:active,
.button.connect-device:active,
#editBookmarkPanelRemoveButton:active,
#PanelUI-panic-view-button:active {
	background-image: linear-gradient(rgba(0, 0, 0, .2), rgba(0, 0, 0, .2)) !important;
}