added border radius to sub menu

scss/_menue.scss

@@ -28,13 +28,14 @@
     left: 50%;
     transform: translateX(-50%);
     background-color: $back-color-3;
+    border-radius: 10px;
 
     a {
         border-bottom: $back-color-2 solid 2px;
         width: 100%;
         color: $text-color;
 
-        &:last-child{
+        &:last-of-type{
             border-bottom: none;
         }
     }