diff --git a/core/css.ts b/core/css.ts
index 20c5730935e..901a17c8e47 100644
--- a/core/css.ts
+++ b/core/css.ts
@@ -139,6 +139,13 @@ let content = `
   z-index: -1;
   background-color: inherit;
   border-color: inherit;
+  border-bottom: 1px solid;
+  border-right: 1px solid;
+  border-bottom-right-radius: 4px;
+  border-color: inherit;
+  border-top: 1px solid;
+  border-left: 1px solid;
+  border-top-left-radius: 4px;
 }
 
 .blocklyDropDownButton {
@@ -153,20 +160,6 @@ let content = `
   cursor: pointer;
 }
 
-.blocklyArrowTop {
-  border-top: 1px solid;
-  border-left: 1px solid;
-  border-top-left-radius: 4px;
-  border-color: inherit;
-}
-
-.blocklyArrowBottom {
-  border-bottom: 1px solid;
-  border-right: 1px solid;
-  border-bottom-right-radius: 4px;
-  border-color: inherit;
-}
-
 .blocklyResizeSE {
   cursor: se-resize;
   fill: #aaa;
diff --git a/core/dropdowndiv.ts b/core/dropdowndiv.ts
index c90661c4ea7..77a246b9ca6 100644
--- a/core/dropdowndiv.ts
+++ b/core/dropdowndiv.ts
@@ -712,9 +712,7 @@ function positionInternal(
       'px) rotate(45deg)';
     arrow.setAttribute(
       'class',
-      metrics.arrowAtTop
-        ? 'blocklyDropDownArrow blocklyArrowTop'
-        : 'blocklyDropDownArrow blocklyArrowBottom',
+      metrics.arrowAtTop ? 'blocklyDropDownArrow' : 'blocklyDropDownArrow',
     );
   } else {
     arrow.style.display = 'none';