update

src/sass/gtk/_common-4.0.scss

@@ -632,41 +632,36 @@ entry {
 }
 
 .entry-tag {
-  $tag_height: $menuitem_size - 4px;
-  $tag_margin: 8px;
-
-  margin: $tag_margin; // instead of min-height: $tag_height;
-  border-radius: 50px;
+  margin: 0;
+  min-height: 16px;
+  border-radius: $circular_radius;
   box-shadow: none;
-  background-color: $destructive_color;
+  background-color: $suggested_color;
   color: $light_fg_color;
   border: none;
+  padding: 2px;
 
-  &:hover { box-shadow: 0 0 0 1px $borders_color; }
+  &:hover { box-shadow: $shadow_4; }
 
   // side margins: compensate the entry padding with a negative margin
   // then the negative margin itself
   :dir(ltr) & {
-    margin-left: 8px;
-    margin-right: $tag_margin - 8px;
-    padding-left: 8px;
-    padding-right: ($tag_height - 16px) / 2;
+    margin-left: $container_padding / 2;
+    margin-right: 0;
   }
 
   :dir(rtl) & {
-    margin-left: $tag_margin - 8px;
-    margin-right: 8px;
-    padding-left: ($tag_height - 16px) / 2;
-    padding-right: 8px;
+    margin-left: 0;
+    margin-right: $container_padding / 2;
   }
 
   // seems any sizing doesn't work
-  &.button {
-    box-shadow: none;
-    border: none;
-    background-color: transparent;
-
-    &:not(:hover):not(:active) { color: $disabled_fg_color; }
+  > button {
+    min-height: 20px;
+    min-width: 20px;
+    padding: 0;
+    border-radius: $circular_radius;
+    @extend %selected-button;
   }
 }
 
@@ -4388,10 +4383,12 @@ stacksidebar {
 
 // Navigation Sidebar
 .navigation-sidebar {
+  background-color: $dark_sidebar_bg;
   padding: $container_padding 0; //only vertical padding. horizontal row size would clip
 
   > separator {
     margin: $container_padding 0;
+    background: none;
   }
 
   > row {

src/sass/gtk/apps/_gnome-40.0.scss

@@ -4,6 +4,18 @@
  ************/
 
  .nautilus-window {
+  flap.unfolded {
+    > separator.horizontal {
+      background-color: $header_border;
+    }
+  }
+
+  flap.folded {
+    > placessidebar {
+      border-right: 1px solid $header_border;
+    }
+  }
+
   // Floating Bar
   .floating-bar {
     padding: 2px;
@@ -13,13 +25,11 @@
     margin: $container_padding;
     box-shadow: $shadow_5;
 
-    button {
-      border: none;
+    > button.circular.flat {
       border-radius: $circular_radius;
-      min-height: 0;
-      min-width: 0;
+      min-height: 24px;
+      min-width: 24px;
       padding: 0;
-      margin-right: container_padding;
       -gtk-icon-shadow: none;
       @extend %selected-button;
     }
@@ -36,6 +46,16 @@
 #NautilusQueryEditor { // search entry
   padding: 1px $container_padding;
 
+  > box { margin: 0; }
+
+  #NautilusQueryEditorTag {
+    @extend .entry-tag;
+
+    > button {
+      margin: 0;
+    }
+  }
+
   > menubutton > button {
     min-width: 16px;
     min-height: 16px;