some assorted edits...

change how the bookmarks toolbar appears in customize mode.
change the size of the sign in item in the app menu.

uc-app-menu.css

@@ -581,6 +581,7 @@ toolbarseparator.proton-zap {
 #appMenu-fxa-status2:not([fxastatus]) {
     margin-inline-end: 0 !important;
     padding-inline-end: var(--arrowpanel-menuitem-inline-margin) !important;
+	padding-block: 0 !important;
 }
 
 #appMenu-fxa-status2:not([fxastatus]) > #appMenu-fxa-label2 {

uc-navbar.css

@@ -290,7 +290,7 @@ toolbar .toolbarbutton-1:not([disabled])[open]:hover > .toolbarbutton-icon {
     background-color: var(--toolbarbutton-active-background) !important;
 }
 
-#PlacesToolbar toolbarbutton.bookmark-item {
+#PersonalToolbar toolbarbutton.bookmark-item {
     padding-inline: var(--toolbarbutton-inner-padding) !important;
 }
 
@@ -355,10 +355,12 @@ toolbar .toolbarbutton-1:not([disabled], [open])[checked]:hover:active > .toolba
     transition: min-height 200ms ease-in-out, max-height 200ms ease-in-out,
         opacity 200ms ease-in-out, transform 200ms ease-in-out !important;
     overflow-y: visible !important;
+    padding-block: 0 var(--bookmark-block-padding) !important;
+    outline: none !important;
 }
 
-#PersonalToolbar:not([customizing]) {
-    padding-block: 0 var(--bookmark-block-padding) !important;
+#PersonalToolbar[customizing][draggingover] {
+    z-index: 4 !important;
 }
 
 #PersonalToolbar #personal-bookmarks {
@@ -494,26 +496,6 @@ toolbarbutton.bookmark-item:not(.subviewbutton) {
     height: 20px !important;
 }
 
-#PersonalToolbar[customizing] #personal-toolbar-empty-description,
-#PersonalToolbar[customizing] .toolbarbutton-1,
-#PersonalToolbar[customizing] toolbarbutton.bookmark-item:not(.subviewbutton) {
-    margin-block: 1.75px !important;
-}
-
-#PersonalToolbar[customizing] {
-    outline: none !important;
-    transition: none !important;
-    border-block: 1px dashed var(--arrowpanel-dimmed-even-further) !important;
-}
-
-#PersonalToolbar[customizing] > toolbarpaletteitem {
-    margin-block: -1px !important;
-}
-
-#PersonalToolbar[customizing][draggingover] {
-    z-index: 4 !important;
-}
-
 #customization-header {
     margin-top: 40px !important;
 }

uc-tabs.css

@@ -753,7 +753,7 @@ so in other words it won't show if audio is playing until you hover the general
         this version of the animation is implemented by an <animateTransform> tag.
         it's the most efficient method but it has broken once for a couple days due to an erroneous nightly patch. */
 
-        /* background-image: url(chrome://userchrome/content/loading-spinner.svg) !important; */
+        background-image: url(chrome://userchrome/content/loading-spinner.svg) !important;
 
         /* ---------------------------------- */
 
@@ -764,7 +764,7 @@ so in other words it won't show if audio is playing until you hover the general
         giving the element a CSS property "animation" that references the animation in the style tag.
         use this if method #1 randomly breaks, *temporarily*. mozilla should patch such a bug quickly. */
 
-        background-image: url(chrome://userchrome/content/loading-spinner-css.svg) !important;
+        /* background-image: url(chrome://userchrome/content/loading-spinner-css.svg) !important; */
 
         /* ---------------------------------- */
 
@@ -784,13 +784,13 @@ so in other words it won't show if audio is playing until you hover the general
 
     /* all tabs menu & vertical tabs pane (script) */
     .tab-throbber-tabslist:is([busy], [progress]) {
-        /* METHOD #1: */
-        /* list-style-image: url(chrome://userchrome/content/loading-spinner.svg) !important; */
+        /* ANIMATION METHOD #1: */
+        list-style-image: url(chrome://userchrome/content/loading-spinner.svg) !important;
 
-        /* METHOD #2: */
-        list-style-image: url(chrome://userchrome/content/loading-spinner-css.svg) !important;
+        /* ANIMATION METHOD #2: */
+        /* list-style-image: url(chrome://userchrome/content/loading-spinner-css.svg) !important; */
 
-        /* METHOD #3: */
+        /* ANIMATION METHOD #3: */
         /* animation: 0.85s steps(12, end) uc-tab-throbber-spinner infinite !important;
         list-style-image: url(chrome://userchrome/content/loading-spinner-static.svg) !important; */
     }

userChrome.au.css

@@ -195,6 +195,13 @@ the last 75% or so of this stylesheet is dedicated to restoring pre-proton conte
         width: calc(var(--panel-width) + 10px);
     }
 
+    #managed-bookmarks > .toolbarbutton-icon,
+    #bookmarks-toolbar-placeholder > .toolbarbutton-icon,
+    #PlacesToolbarItems > .bookmark-item > .toolbarbutton-icon[label]:not([label=""]),
+    #OtherBookmarks.bookmark-item[container] > .toolbarbutton-icon {
+        margin-inline-end: var(--context-iconic-margin-end);
+    }
+
     /* panel width */
     #customizationui-widget-multiview panelview:not([extension]) {
         width: unset;