update

src/sass/gnome-shell/extensions-40-0/_dash-to-dock.scss

@@ -13,6 +13,7 @@
 
 #dashtodockContainer {
   background-color: transparent;
+  box-shadow: none;
 
   .number-overlay {
     color: $light_fg_color;
@@ -31,38 +32,25 @@
     text-align: center;
   }
 
-  &.straight-corner #dash,
-  &.shrink.straight-corner #dash {
-    border-radius: 0;
-    border-left: 0;
-    border-right: 0;
-    padding-top: 0;
-    padding-bottom: 0;
-    margin-top: 0;
+  @each $_pos, $b_pos, $_shadow in (top, bottom, 0 -1px),
+                                   (bottom, top, 0 1px),
+                                   (left, right, -1px 0),
+                                   (right, left, 1px 0) {
+    &.#{$_pos}.shrink #dash,
+    &.#{$_pos}.shrink:overview #dash,
+    &.#{$_pos}.straight-corner #dash,
+    &.#{$_pos}.shrink.straight-corner #dash,
+    &.#{$_pos}.extended #dash,
+    &.#{$_pos}.extended:overview #dash {
+      margin: 0 !important;
+      padding: 0 !important;
 
       .dash-background {
         border-radius: 0;
-      margin-bottom: 0;
-    }
-  }
-
-  &.extended.top,
-  &.extended.bottom,
-  &.extended.right,
-  &.extended.left {
-    #dash {
-      margin-left: 0;
-      margin-right: 0;
-      margin-top: 0;
-      margin-bottom: 0;
-      padding: 0 0;
-
-      .dash-background {
-        border-radius: 0;
-        margin-left: 0;
-        margin-right: 0;
-        margin-top: 0;
-        margin-bottom: 0;
+        border-width: 0;
+        border-#{$b_pos}-width: 1px;
+        margin: 0 !important;
+        box-shadow: inset #{$_shadow} rgba(white, 0.05);
       }
     }
   }
@@ -70,29 +58,23 @@
   &.left,
   &.right {
     #dash {
-      margin-top: 0;
-      padding: $dash_padding 0;
+      margin-top: 0 !important;
+      padding: $dash_padding !important;
 
-      .dash-background { // default-mode
-        margin-bottom: 0;
-      }
+      .dash-background {
+        margin-bottom: 0 !important;
+        padding: $dash_padding !important;
       }
 
       .dash-item-container .app-well-app, .show-apps {
-      padding: $base_padding;
+        padding: $dash_spacing $base_padding !important;
       }
     }
-
-  &.left #dash {
-    margin-left: $base_padding;
-  }
-
-  &.right #dash {
-    margin-right: $base_padding;
   }
 
   #dash { // default-mode
     background: none;
+    box-shadow: none;
 
     StWidget.focused .app-well-app-running-dot {
       background-color: $primary_color;
@@ -154,12 +136,12 @@
   &.opaque:overview,
   &.transparent:overview { // overview-mode #2
     #dash {
-      background-color: transparent !important;
-      box-shadow: none !important;
+      background-color: transparent;
+      box-shadow: none;
     }
 
     .dash-background {
-      background-color: transparent !important;
+      background-color: transparent;
     }
   }
 
@@ -169,6 +151,12 @@
     #dash {
       background: none;
     }
+
+    .dash-background {
+      background-color: transparent !important;
+      border: none !important;
+      box-shadow: none !important;
+    }
   }
 
   &.running-dots,

src/sass/gnome-shell/widgets-40-0/_dash.scss

@@ -24,7 +24,6 @@ $dash_border_radius: $dash_padding * 1.5 + 12px;
   .app-well-app-running-dot {
     background-color: if($variant == 'light', rgba(black, 0.75), rgba(white, 0.75));
   }
-}
 
   .dash-background {
     background-color: $dash_background_color;
@@ -43,3 +42,4 @@ $dash_border_radius: $dash_padding * 1.5 + 12px;
     margin: 0 ($dash_spacing + ($dash_padding / 2)) $dash_bottom_margin;
     background-color: rgba(white, 0.25);
   }
+}

tweaks.sh

@@ -138,7 +138,6 @@ while [[ $# -gt 0 ]]; do
       fi; shift ;;
     -d|--dash-to-dock)
       if [[ "${GNOME_VERSION}" == 'new'  ]]; then
-        prompt -w "'${1}' It will install a fixed version on GNOME-SHELL >= 40.0"
         dash_to_dock="new"
       elif [[ ! -d "${DASH_TO_DOCK_DIR_HOME}" && ! -d "${DASH_TO_DOCK_DIR_ROOT}" ]]; then
         prompt -e "'${1}' ERROR: There's no Dash to Dock installed in your system"