no select scrollbar with dividers

packages/core/src/components/menu/_common.scss

@@ -305,9 +305,15 @@ $dark-menu-item-intent-colors: (
 @mixin menu-divider() {
   border-top: 1px solid $pt-divider-black;
   display: block;
-  // use negative margin to make dividers take up full menu width
+  // use negative margin to make dividers take up full menu width... (see below)
   margin: $half-grid-size (-$half-grid-size);
 
+  // ... unless inside a select popover, which needs to provide negative margin on the
+  // parent menu component to offset padding added inside the select popover
+  .#{$ns}-select-popover & {
+    margin: $half-grid-size 0;
+  }
+
   .#{$ns}-dark & {
     border-top-color: $pt-dark-divider-white;
   }

packages/select/src/components/select/_select.scss

@@ -3,11 +3,13 @@
 
 @import "../../common/variables";
 
+$select-padding: $pt-grid-size * 0.5;
+
 .#{$ns}-select-popover {
   .#{$ns}-popover-content {
     // use padding on container rather than margin on input group
     // because top margin leaves some empty space with no background color.
-    padding: $pt-grid-size * 0.5;
+    padding: $select-padding;
   }
 
   .#{$ns}-input-group {
@@ -19,10 +21,13 @@
     max-width: $select-popover-max-width;
     overflow: auto;
     padding: 0;
+    margin-left: -$select-padding;
+    margin-right: -$select-padding;
+    margin-bottom: -$select-padding;
 
     &:not(:first-child) {
       // adjust padding to account for that on .#{$ns}-popover-content above
-      padding-top: $pt-grid-size * 0.5;
+      padding-top: $select-padding;
     }
   }