diff --git a/gtk/theme/Adwaita/_common.scss b/gtk/theme/Adwaita/_common.scss
index 25e591b203..4ad4c8d80c 100644
--- a/gtk/theme/Adwaita/_common.scss
+++ b/gtk/theme/Adwaita/_common.scss
@@ -1069,7 +1069,10 @@ spinbutton {
         background-color: $base_hover_color;
       }
 
-      &:disabled { color: transparentize($insensitive_fg_color, 0.7); }
+      &:disabled {
+        color: transparentize($insensitive_fg_color, 0.7);
+        background-color: transparent;
+      }
 
       &:active {
         background-color: transparentize(black, 0.9);
@@ -1090,6 +1093,10 @@ spinbutton {
 
         &:dir(rtl) { border-style: none solid none none; }
       }
+
+      &:dir(ltr):last-child { border-radius: 0 3px 3px 0; }
+
+      &:dir(rtl):first-child { border-radius: 3px 0 0 3px; }
     }
   }
 
@@ -1135,7 +1142,7 @@ spinbutton {
         box-shadow: none;
       }
 
-      &:last-child { border-radius: 0 3px 3px 0; }
+      &:dir(ltr):last-child { border-radius: 0 3px 3px 0; }
 
       &:dir(rtl):first-child { border-radius: 3px 0 0 3px; }
     }
diff --git a/gtk/theme/Adwaita/gtk-contained-dark.css b/gtk/theme/Adwaita/gtk-contained-dark.css
index 8560559f63..39eed681f4 100644
--- a/gtk/theme/Adwaita/gtk-contained-dark.css
+++ b/gtk/theme/Adwaita/gtk-contained-dark.css
@@ -1501,7 +1501,8 @@ spinbutton:not(.vertical) {
       color: #eeeeec;
       background-color: rgba(238, 238, 236, 0.05); }
     spinbutton:not(.vertical) button:disabled {
-      color: rgba(148, 151, 150, 0.3); }
+      color: rgba(148, 151, 150, 0.3);
+      background-color: transparent; }
     spinbutton:not(.vertical) button:active {
       background-color: rgba(0, 0, 0, 0.1);
       box-shadow: inset 0 2px 3px -1px rgba(0, 0, 0, 0.2); }
@@ -1516,6 +1517,10 @@ spinbutton:not(.vertical) {
       border-style: none none none solid; }
       spinbutton:not(.vertical) button:backdrop:disabled:dir(rtl) {
         border-style: none solid none none; }
+    spinbutton:not(.vertical) button:dir(ltr):last-child {
+      border-radius: 0 3px 3px 0; }
+    spinbutton:not(.vertical) button:dir(rtl):first-child {
+      border-radius: 3px 0 0 3px; }
 .osd spinbutton:not(.vertical) button {
   border-color: transparent;
   background-color: transparent;
@@ -1565,7 +1570,7 @@ spinbutton:not(.vertical) {
     border-color: rgba(0, 0, 0, 0.5);
     -gtk-icon-shadow: none;
     box-shadow: none; }
-  .osd spinbutton:not(.vertical) button:last-child {
+  .osd spinbutton:not(.vertical) button:dir(ltr):last-child {
     border-radius: 0 3px 3px 0; }
   .osd spinbutton:not(.vertical) button:dir(rtl):first-child {
     border-radius: 3px 0 0 3px; }
diff --git a/gtk/theme/Adwaita/gtk-contained.css b/gtk/theme/Adwaita/gtk-contained.css
index 7dc267f841..83fd3b3099 100644
--- a/gtk/theme/Adwaita/gtk-contained.css
+++ b/gtk/theme/Adwaita/gtk-contained.css
@@ -1508,7 +1508,8 @@ spinbutton:not(.vertical) {
       color: #2e3436;
       background-color: rgba(46, 52, 54, 0.05); }
     spinbutton:not(.vertical) button:disabled {
-      color: rgba(139, 142, 143, 0.3); }
+      color: rgba(139, 142, 143, 0.3);
+      background-color: transparent; }
     spinbutton:not(.vertical) button:active {
       background-color: rgba(0, 0, 0, 0.1);
       box-shadow: inset 0 2px 3px -1px rgba(0, 0, 0, 0.2); }
@@ -1523,6 +1524,10 @@ spinbutton:not(.vertical) {
       border-style: none none none solid; }
       spinbutton:not(.vertical) button:backdrop:disabled:dir(rtl) {
         border-style: none solid none none; }
+    spinbutton:not(.vertical) button:dir(ltr):last-child {
+      border-radius: 0 3px 3px 0; }
+    spinbutton:not(.vertical) button:dir(rtl):first-child {
+      border-radius: 3px 0 0 3px; }
 .osd spinbutton:not(.vertical) button {
   border-color: transparent;
   background-color: transparent;
@@ -1572,7 +1577,7 @@ spinbutton:not(.vertical) {
     border-color: rgba(0, 0, 0, 0.5);
     -gtk-icon-shadow: none;
     box-shadow: none; }
-  .osd spinbutton:not(.vertical) button:last-child {
+  .osd spinbutton:not(.vertical) button:dir(ltr):last-child {
     border-radius: 0 3px 3px 0; }
   .osd spinbutton:not(.vertical) button:dir(rtl):first-child {
     border-radius: 3px 0 0 3px; }