Merge pull request #2119 from Shopify/fix-dropzone-contrast

[Drop zone][a11y] Fixed border colour to have better contrast

UNRELEASED.md

@@ -10,6 +10,7 @@ Use [the changelog guidelines](https://git.io/polaris-changelog-guidelines) to f
 
 ### Enhancements
 
+- Changed border color of `Drop zone` to have better contrast from the background and to be lighter when disabled ([#2119](https://github.com/Shopify/polaris-react/pull/2119))
 - Adjusted search results overlay to take up 100% height of the screen on small screens and to match the width of the search bar on large screens. ([#2103](https://github.com/Shopify/polaris-react/pull/2103))
 - Added skipToContentTarget prop to Frame component ([#2080](https://github.com/Shopify/polaris-react/pull/2080))
 

src/components/DropZone/DropZone.scss

@@ -2,7 +2,8 @@
 
 $dropzone-padding: rem(15px);
 $dropzone-border-style: dashed;
-$dropzone-border-color: color('sky');
+$dropzone-border-color: color('ink', 'lightest');
+$dropzone-border-color-disabled: color('sky');
 $dropzone-border-radius: border-radius();
 $dropzone-background: color('white');
 $dropzone-min-height-extra-large: rem(205px);
@@ -90,6 +91,10 @@ $dropzone-stacking-order: (
 
 .isDisabled {
   cursor: not-allowed;
+
+  &::after {
+    border-color: $dropzone-border-color-disabled;
+  }
 }
 
 .sizeExtraLarge {