--- a/browser/themes/linux/customizableui/panelUI.css
+++ b/browser/themes/linux/customizableui/panelUI.css
@@ -21,43 +21,16 @@
   padding-top: 1px;
 }
 
 /* Add some space at the top because there are no headers: */
 #BMB_bookmarksPopup menupopup > hbox > .popup-internal-box > .arrowscrollbox-scrollbox > .scrollbox-innerbox  {
   padding-top: 4px;
 }
 
-.subviewbutton > .toolbarbutton-text {
-  padding-top: 3px;
-  padding-bottom: 3px;
-}
-
-.widget-overflow-list .toolbarbutton-1 > .toolbarbutton-menubutton-button {
-  -moz-appearance: none;
-  border: 0;
-  margin-inline-start: 3px;
-}
-
-.widget-overflow-list .toolbarbutton-1 > .toolbarbutton-menubutton-dropmarker {
-  margin-inline-start: 0;
-}
-
-.subviewbutton > .toolbarbutton-text {
-  padding-inline-start: 16px;
-}
-
-.subviewbutton:-moz-any([image],[targetURI],.cui-withicon, .restoreallitem, .bookmark-item) > .toolbarbutton-text {
-  padding-inline-start: 0;
-}
-
-.subviewbutton:-moz-any([image],[targetURI],.cui-withicon, .restoreallitem, .bookmark-item)[checked="true"] > .toolbarbutton-icon {
-  visibility: hidden;
-}
-
 menuitem.subviewbutton {
   -moz-appearance: none !important;
 }
 
 menu.subviewbutton > .menu-right {
   -moz-appearance: none;
   list-style-image: url(chrome://browser/skin/places/bookmarks-menu-arrow.png);
   -moz-image-region: rect(0, 16px, 16px, 0);
@@ -68,57 +41,22 @@ menu.subviewbutton > .menu-right {
 menu[disabled="true"].subviewbutton > .menu-right {
   -moz-image-region: rect(0, 32px, 16px, 16px);
 }
 
 menu.subviewbutton > .menu-right:-moz-locale-dir(rtl) {
   transform: scaleX(-1);
 }
 
-.subviewbutton > .toolbarbutton-icon {
-  margin-inline-end: 5px;
-}
-
-.subviewbutton > .menu-right,
-.subviewbutton > .menu-iconic-left {
-  padding-top: 1px;
-  /* These need !important to override menu.css */
-  margin-top: 1px !important;
-  margin-bottom: 2px !important;
-}
-
 .subviewradio > .radio-label-box {
   -moz-appearance: none;
 }
 
 /*
  * #pageActionFeedbackAnimatableImage is wider than the panel, and due to a
  * bug in panels on Linux, a box-shadow appears where the image would be if
  * overflow:hidden wasn't applied. Disabling the box-shadow for this panel on
  * Linux works around this issue. This bug is on file as 1394575.
  */
 #pageActionFeedback > .panel-arrowcontainer > .panel-arrowcontent {
   box-shadow: none;
 }
 
-/* START photon adjustments */
-
-photonpanelmultiview .subviewbutton > .toolbarbutton-text,
-photonpanelmultiview .subviewbutton > .toolbarbutton-icon,
-photonpanelmultiview .panel-banner-item > .toolbarbutton-multiline-text {
-  margin: 0;
-}
-
-photonpanelmultiview .subviewbutton > .toolbarbutton-icon {
-  padding: 0;
-}
-
-photonpanelmultiview .subviewbutton:-moz-any([image],[targetURI],.cui-withicon,
-  .restoreallitem, .bookmark-item) > .toolbarbutton-text {
-  padding-inline-start: 8px;
-}
-
-photonpanelmultiview .subviewbutton:-moz-any([image],[targetURI],.cui-withicon,
-  .restoreallitem, .bookmark-item)[checked="true"] > .toolbarbutton-icon {
-  visibility: visible;
-}
-
-/* END photon adjustments */

--- a/browser/themes/osx/customizableui/panelUI.css
+++ b/browser/themes/osx/customizableui/panelUI.css
@@ -3,93 +3,55 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 %include ../../shared/customizableui/panelUI.inc.css
 
 .panel-subviews {
   background-color: hsla(0,0%,100%,.97);
 }
 
-.panelUI-grid .toolbarbutton-1 {
-  margin-right: 0;
-  margin-left: 0;
-  margin-bottom: 0;
-}
-
-.subviewbutton > .toolbarbutton-text {
-  margin: 2px 0 !important; /* !important for overriding toolbarbutton.css */
-}
-
-.subviewbutton:-moz-any([image],[targetURI],.cui-withicon, .bookmark-item) > .toolbarbutton-text {
-  margin: 2px 6px !important; /* !important for overriding toolbarbutton.css */
-}
-
-/* START photon adjustments */
-
-photonpanelmultiview .subviewbutton > .toolbarbutton-text,
-photonpanelmultiview .subviewbutton:-moz-any([image],[targetURI],.cui-withicon, .bookmark-item) > .toolbarbutton-text,
-photonpanelmultiview .panel-banner-item > .toolbarbutton-multiline-text {
-  margin: 0 !important;  /* !important for overriding the rules above. */
-}
-
-/* END photon adjustments */
-
 .restoreallitem > .toolbarbutton-icon {
   display: none;
 }
 
 .subviewbutton {
   padding-inline-start: 18px;
 }
 
 .subviewbutton[checked="true"] {
-  background-position: top 5px left 4px;
+  background-position: top 7px left 4px;
 }
 
 .subviewbutton[checked="true"]:-moz-locale-dir(rtl) {
-  background-position: top 5px right 4px;
+  background-position: top 7px right 4px;
 }
 
 .subviewbutton:not(:-moz-any([image],[targetURI],.cui-withicon, .bookmark-item)) > .menu-iconic-left {
   display: none;
 }
 
-menu.subviewbutton,
-menuitem.subviewbutton:not(.panel-subview-footer) {
-  padding-top: 2px;
-  padding-bottom: 2px;
-}
-
 /* Override OSX-specific toolkit styles for the bookmarks panel */
 menu.subviewbutton > .menu-right {
   margin-inline-end: 0;
   -moz-appearance: none;
 }
 
 menu.subviewbutton > .menu-right > image {
  /* We don't want the arrow to highlight when the .subviewbutton is hovered,
   * so we set the -moz-appearance rule on the image
   * (which doesn't inherit the _moz-menuactive attribute) instead.
   */
   -moz-appearance: menuarrow;
 }
 
-.widget-overflow-list .toolbarbutton-1 > .toolbarbutton-menubutton-dropmarker {
-  margin-inline-start: 4px;
-}
-
 .PanelUI-subView menuseparator,
 .cui-widget-panelview menuseparator {
   padding: 0 !important;
 }
 
-toolbarpaletteitem[place="palette"] > .toolbarbutton-1 > .toolbarbutton-menubutton-button {
-  padding: 3px 1px;
-}
-
 #PanelUI-remotetabs-tabslist > label[itemtype="client"] {
   padding-inline-start: 6px;
 }
 
 .PanelUI-remotetabs-notabsforclient-label {
   margin-left: 19px;
   font-size: 13px;
 }

--- a/browser/themes/shared/customizableui/panelUI.inc.css
+++ b/browser/themes/shared/customizableui/panelUI.inc.css
@@ -1187,65 +1187,85 @@ toolbaritem[cui-areatype="menu-panel"][s
   background-color: hsl(109,65%,22%);
 }
 
 #customization-palette .toolbarbutton-multiline-text,
 #customization-palette .toolbarbutton-text {
   display: none;
 }
 
-panelview .toolbarbutton-1,
-.subviewbutton,
-.widget-overflow-list .toolbarbutton-1,
-.panelUI-grid .toolbarbutton-1 > .toolbarbutton-menubutton-button {
-  -moz-appearance: none;
-  padding: 0 6px;
-  background-color: transparent;
-  border-radius: 2px;
-  border-style: solid;
-  border-color: transparent;
-}
-
+.subview-subheader,
 panelview .toolbarbutton-1,
 .subviewbutton,
 .widget-overflow-list .toolbarbutton-1 {
-  border-width: 1px;
+  -moz-appearance: none;
+  margin: 0;
+  min-height: 24px;
+  padding: 4px 12px;
+  background-color: transparent;
+}
+
+.subviewbutton:focus {
+  outline: 0;
+}
+
+.subviewbutton > .toolbarbutton-text {
+  padding: 0;
+  padding-inline-start: 24px; /* This is 16px for the icon + 8px for the padding as defined above. */
+}
+
+.subviewbutton > .menu-right,
+.subviewbutton > .menu-accel-container > .menu-iconic-accel,
+.subviewbutton > .menu-iconic-left,
+.subviewbutton > .menu-iconic-text {
+  padding-bottom: 0;
+  padding-top: 0;
 }
 
-.subviewbutton.panel-subview-footer {
-  border-radius: 0;
-  border: none;
+.subviewbutton-iconic > .toolbarbutton-text,
+.cui-withicon > .toolbarbutton-text,
+.subviewbutton[image] > .toolbarbutton-text,
+.subviewbutton[targetURI] > .toolbarbutton-text,
+.subviewbutton.restoreallitem > .toolbarbutton-text,
+.subviewbutton.bookmark-item > .toolbarbutton-text,
+.subviewbutton[checked="true"] > .toolbarbutton-text {
+  padding-inline-start: 8px; /* See '.subviewbutton-iconic > .toolbarbutton-text' rule above. */
+}
+
+.panel-banner-item > .toolbarbutton-multiline-text {
+  font: menu;
+  margin: 0;
+  padding: 0;
+  padding-inline-start: 8px; /* See '.subviewbutton-iconic > .toolbarbutton-text' rule above. */
+}
+
+.subviewbutton-iconic > .toolbarbutton-icon {
+  width: 16px;
+  height: 16px;
+  -moz-context-properties: fill;
+  fill: currentColor;
+}
+
+/* We don't always display: none this item, and if it has forced width (like above)
+ * or margin, that impacts the position of the label. Fix:
+ */
+.subviewbutton > .toolbarbutton-icon {
+  margin: 0;
 }
 
 .subviewbutton.panel-subview-footer > .menu-text {
   -moz-appearance: none;
-  margin-inline-start: 0px !important;
-  padding-inline-start: 6px;
   padding-inline-end: 6px;
   -moz-box-flex: 0;
-  text-align: center;
-}
-
-.subviewbutton.panel-subview-footer > .toolbarbutton-icon {
-  margin: 0;
-}
-
-panelview:not([mainView]) .subviewbutton.panel-subview-footer > .toolbarbutton-text {
-  text-align: center;
-  padding: 0;
 }
 
 .subviewbutton.panel-subview-footer > .menu-accel-container {
   padding-inline-start: 6px;
 }
 
-.subviewbutton:not(.panel-subview-footer) {
-  margin: 0;
-}
-
 #widget-overflow-fixed-list .toolbarbutton-1 > .toolbarbutton-text,
 #widget-overflow-list .toolbarbutton-1 > .toolbarbutton-text,
 .subviewbutton:not(.panel-subview-footer) > .toolbarbutton-text,
 /* Bookmark items need a more specific selector. */
 .PanelUI-subView .subviewbutton:not(.panel-subview-footer) > .menu-text,
 .PanelUI-subView .subviewbutton:not(.panel-subview-footer) > .menu-iconic-text {
   font: menu;
 }
@@ -1275,65 +1295,18 @@ panelview:not([mainView]) .subviewbutton
 }
 
 /* This is a <label> but it should fit in with the menu font- and colorwise. */
 #PanelUI-characterEncodingView-autodetect-label {
   font: menu;
   color: inherit;
 }
 
-.cui-widget-panelview .subviewbutton:not(.panel-subview-footer) {
-  margin-left: 4px;
-  margin-right: 4px;
-}
-
 /* START photon adjustments */
 
-.widget-overflow-list > toolbarpaletteitem[place=panel] .toolbarbutton-1,
-photonpanelmultiview .widget-overflow-list .toolbarbutton-1,
-photonpanelmultiview .PanelUI-subView .subviewbutton,
-photonpanelmultiview .cui-widget-panelview .subviewbutton:not(.panel-subview-footer),
-photonpanelmultiview .subview-subheader {
-  border-radius: 0;
-  border-width: 0;
-  margin: 0;
-  padding: 4px 12px;
-}
-
-photonpanelmultiview .subviewbutton:focus {
-  outline: 0;
-}
-
-photonpanelmultiview .subviewbutton > .toolbarbutton-text {
-  padding: 0;
-  padding-inline-start: 24px; /* This is 16px for the icon + 8px for the padding as defined above. */
-}
-
-photonpanelmultiview .subviewbutton-iconic > .toolbarbutton-text,
-photonpanelmultiview .cui-withicon > .toolbarbutton-text,
-photonpanelmultiview .subviewbutton[image] > .toolbarbutton-text,
-photonpanelmultiview .subviewbutton[checked="true"] > .toolbarbutton-text {
-  padding-inline-start: 8px; /* See '.subviewbutton-iconic > .toolbarbutton-text' rule above. */
-}
-
-photonpanelmultiview .panel-banner-item > .toolbarbutton-multiline-text {
-  font: menu;
-  padding: 0;
-  padding-inline-start: 8px; /* See '.subviewbutton-iconic > .toolbarbutton-text' rule above. */
-}
-
-photonpanelmultiview .subviewbutton-iconic > .toolbarbutton-icon {
-  width: 16px;
-}
-
-photonpanelmultiview .subviewbutton {
-  -moz-context-properties: fill;
-  fill: currentColor;
-}
-
 photonpanelmultiview .subviewbutton[checked="true"] {
   background: none;
   list-style-image: url(chrome://browser/skin/check.svg);
 }
 
 photonpanelmultiview .subviewbutton > .menu-iconic-left {
   -moz-appearance: none;
   margin-inline-end: 0;
@@ -1401,48 +1374,38 @@ photonpanelmultiview .subview-subheader 
   color: GrayText;
 }
 
 photonpanelmultiview .subview-subheader,
 photonpanelmultiview .panel-subview-footer {
   font: menu;
 }
 
-photonpanelmultiview panelview:not([mainView]) .subviewbutton.panel-subview-footer > .toolbarbutton-text {
-  text-align: start;
-}
-
 /* END photon adjustments */
 
 panelview .toolbarbutton-1 {
   margin-top: 6px;
 }
 
 panelview .toolbarbutton-1@buttonStateHover@,
 toolbarbutton.subviewbutton@buttonStateHover@,
 menu.subviewbutton@menuStateHover@,
 menuitem.subviewbutton@menuStateHover@,
 .widget-overflow-list .toolbarbutton-1@buttonStateHover@,
 .toolbaritem-combined-buttons@inAnyPanel@ > toolbarbutton@buttonStateHover@ {
   background-color: var(--arrowpanel-dimmed);
-  border-color: var(--panel-separator-color);
-}
-
-.toolbaritem-combined-buttons@inAnyPanel@@buttonStateHover@ {
-  border-color: var(--panel-separator-color);
 }
 
 panelview .toolbarbutton-1:-moz-any(@buttonStateActive@,[checked=true]),
 toolbarbutton.subviewbutton@buttonStateActive@,
 menu.subviewbutton@menuStateActive@,
 menuitem.subviewbutton@menuStateActive@,
 .widget-overflow-list .toolbarbutton-1@buttonStateActive@,
 .toolbaritem-combined-buttons@inAnyPanel@ > toolbarbutton@buttonStateActive@ {
   background-color: var(--arrowpanel-dimmed-further);
-  border-color: var(--panel-separator-color);
   box-shadow: 0 1px 0 hsla(210,4%,10%,.03) inset;
 }
 
 .subviewbutton.panel-subview-footer {
   margin: 0;
   background-color: var(--arrowpanel-dimmed);
   border-top: 1px solid var(--panel-separator-color);
   border-radius: 0;
@@ -1705,24 +1668,22 @@ toolbarpaletteitem[place=panel] > .toolb
 toolbaritem[overflowedItem=true],
 .widget-overflow-list .toolbarbutton-1 {
   width: 100%;
   max-width: @wideMenuPanelWidth@;
   background-repeat: no-repeat;
   background-position: 0 center;
 }
 
-.widget-overflow-list .toolbarbutton-1,
-.widget-overflow-list .toolbarbutton-1 > .toolbarbutton-menubutton-button {
+.widget-overflow-list .toolbarbutton-1 {
   -moz-box-align: center;
   -moz-box-orient: horizontal;
 }
 
-.widget-overflow-list .toolbarbutton-1:not(.toolbarbutton-combined) > .toolbarbutton-text,
-.widget-overflow-list .toolbarbutton-1 > .toolbarbutton-menubutton-button > .toolbarbutton-text {
+.widget-overflow-list .toolbarbutton-1:not(.toolbarbutton-combined) > .toolbarbutton-text {
   text-align: start;
   padding-inline-start: .5em;
 }
 
 .subviewbutton[checked="true"] {
   background: url("chrome://global/skin/menu/shared-menu-check.png") center left 7px / 11px 11px no-repeat transparent;
 }
 
@@ -2029,20 +1990,16 @@ menuitem[checked="true"].subviewbutton >
 
   #PanelUI-menu-button[badge-status="update-available"] > .toolbarbutton-badge-stack > .toolbarbutton-badge,
   #PanelUI-menu-button[badge-status="update-manual"] > .toolbarbutton-badge-stack > .toolbarbutton-badge,
   #PanelUI-menu-button[badge-status="update-restart"] > .toolbarbutton-badge-stack > .toolbarbutton-badge {
     border: 1px solid -moz-dialog;
   }
 }
 
-.subviewbutton-iconic > .toolbarbutton-text {
-  padding-inline-start: 5px;
-}
-
 /* START photon adjustments */
 
 .panel-header {
   align-items: center;
   border-bottom: 1px solid var(--panel-separator-color);
   display: flex;
   flex: 1 auto;
   height: 40px; /* fixed item height to prevent flex sizing; height + 2*4px padding */

--- a/browser/themes/shared/sidebar.inc.css
+++ b/browser/themes/shared/sidebar.inc.css
@@ -96,18 +96,19 @@
   display: none;
 }
 
 %ifndef XP_MACOSX
 /* Allow room for the checkbox drawn as a background image at the start of the toolbarbutton */
 #sidebarMenu-popup .subviewbutton-iconic > .toolbarbutton-icon {
   margin-inline-start: 16px;
 }
-#sidebarMenu-popup .subviewbutton-iconic > .toolbarbutton-text {
-  padding-inline-start: 0;
+/* Align items without icons to the start of the icons: */
+#sidebarMenu-popup .subviewbutton:not(.subviewbutton-iconic) > .toolbarbutton-text {
+  padding-inline-start: 16px;
 }
 %endif
 
 
 #sidebar-box[sidebarcommand="viewWebPanelsSidebar"] > #sidebar-header > #sidebar-switcher-target > #sidebar-icon {
   list-style-image: url(chrome://mozapps/skin/places/defaultFavicon.svg);
 }
 

--- a/browser/themes/windows/customizableui/panelUI.css
+++ b/browser/themes/windows/customizableui/panelUI.css
@@ -3,109 +3,57 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 %include ../../shared/customizableui/panelUI.inc.css
 
 .panel-subviews {
   background-color: var(--arrowpanel-background);
 }
 
-#PanelUI-contents #zoom-out-btn {
-  padding-left: 12px;
-  padding-right: 12px;
-}
-
-#PanelUI-contents #zoom-in-btn {
-  padding-left: 12px;
-  padding-right: 12px;
-}
-
 /* bookmark panel submenus */
 
 #BMB_bookmarksPopup menupopup[placespopup=true] {
   -moz-appearance: none;
   background: transparent;
   border: none;
-  padding: 6px;
+  padding: 0;
+  padding-top: 4px;
+  padding-inline-start: 3px;
 }
 
 #BMB_bookmarksPopup menupopup[placespopup=true] > hbox {
   /* emulating chrome://browser/content/places/menu.xml#places-popup-arrow but without the arrow */
   box-shadow: 0 0 4px rgba(0,0,0,0.2);
   background: var(--arrowpanel-background);
   color: var(--arrowpanel-color);
   border: 1px solid var(--arrowpanel-border-color);
   border-radius: 3.5px;
   margin-top: -4px;
 }
 
-#BMB_bookmarksPopup menupopup {
-  padding-top: 2px;
-}
-
 /* Add some space at the top because there are no headers: */
 #BMB_bookmarksPopup menupopup[placespopup=true] > hbox > .popup-internal-box > .arrowscrollbox-scrollbox > .scrollbox-innerbox  {
   padding-top: 4px;
 }
 
 /* bookmark panel separator */
 #BMB_bookmarksPopup menuseparator {
   padding-top: 0;
   padding-bottom: 0;
 }
 
-.subviewbutton > .menu-right,
-.subviewbutton > .menu-iconic-left {
-  padding-top: 1px;
-  margin-top: 1px;
-  margin-bottom: 2px;
-}
-
 /* Disabled empty item looks too small otherwise, because it has no icon. */
 menuitem.subviewbutton[disabled]:not(.menuitem-iconic),
 /* Same for checkbox menu items, whose icons lose size due to -moz-appearance: none: */
 menuitem[type="checkbox"].subviewbutton {
   /* This is 16px for an icon + 3px for its margins + 1px for its padding +
    * 2px for its border, see above */
   min-height: 22px;
 }
 
-.subviewbutton > .toolbarbutton-text {
-  padding-top: 3px;
-  padding-bottom: 3px;
-}
-
-.widget-overflow-list .toolbarbutton-1 > .toolbarbutton-menubutton-button {
-  -moz-appearance: none;
-  border: 0;
-  margin-inline-start: 3px;
-}
-
-.widget-overflow-list .toolbarbutton-1 > .toolbarbutton-menubutton-dropmarker {
-  padding: 0 2px;
-  padding-inline-start: 0;
-  height: 18px;
-}
-
-.widget-overflow-list .toolbarbutton-1 > .toolbarbutton-menubutton-dropmarker > .dropmarker-icon {
-  padding: 0 6px;
-}
-
-.subviewbutton > .toolbarbutton-text {
-  padding-inline-start: 16px;
-}
-
-.subviewbutton:-moz-any([image],[targetURI],.cui-withicon, .restoreallitem, .bookmark-item) > .toolbarbutton-text {
-  padding-inline-start: 0;
-}
-
-.subviewbutton:-moz-any([image],[targetURI],.cui-withicon, .restoreallitem, .bookmark-item)[checked="true"] > .toolbarbutton-icon {
-  visibility: hidden;
-}
-
 menu.subviewbutton > .menu-right {
   -moz-appearance: none;
   list-style-image: url(chrome://browser/skin/customizableui/menu-arrow.svg);
   -moz-context-properties: fill;
   fill: MenuText;
   /* Reset the rect we inherit from the button: */
   -moz-image-region: auto;
 }
@@ -121,44 +69,17 @@ menu[disabled="true"].subviewbutton > .m
 }
 
 menu.subviewbutton > .menu-right:-moz-locale-dir(rtl) {
   transform: scaleX(-1);
 }
 
 /* Win8 and beyond. */
 @media not all and (-moz-os-version: windows-win7) {
-  panelview .toolbarbutton-1,
-  .subviewbutton,
-  .widget-overflow-list .toolbarbutton-1,
-  .panelUI-grid .toolbarbutton-1 > .toolbarbutton-menubutton-button,
   #BMB_bookmarksPopup menupopup[placespopup=true] > hbox,
   #edit-controls@inAnyPanel@,
   #zoom-controls@inAnyPanel@,
   #edit-controls@inAnyPanel@ > toolbarbutton,
   #zoom-controls@inAnyPanel@ > toolbarbutton {
     border-radius: 0;
   }
 }
 
-/* START photon adjustments */
-
-photonpanelmultiview .subviewbutton > .toolbarbutton-text,
-photonpanelmultiview .subviewbutton > .toolbarbutton-icon,
-photonpanelmultiview .panel-banner-item > .toolbarbutton-multiline-text {
-  margin: 0;
-}
-
-photonpanelmultiview .subviewbutton > .toolbarbutton-icon {
-  padding: 0;
-}
-
-photonpanelmultiview .subviewbutton:-moz-any([image],[targetURI],.cui-withicon,
-  .restoreallitem, .bookmark-item) > .toolbarbutton-text {
-  padding-inline-start: 8px;
-}
-
-photonpanelmultiview .subviewbutton:-moz-any([image],[targetURI],.cui-withicon,
-  .restoreallitem, .bookmark-item)[checked="true"] > .toolbarbutton-icon {
-  visibility: visible;
-}
-
-/* END photon adjustments */