feat(storefront): BCTHEME-275 add upsell banner contrast (#1891)

Co-authored-by: BC-tymurbiedukhin <66319629+BC-tymurbiedukhin@users.noreply.github.com>

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Changelog
 
 ## Draft
+- Add sufficient contrast for Upsell Banners in Cornerstone Theme according to AA Standard. [#1891](https://github.com/bigcommerce/cornerstone/pull/1891)
 - Add appropriate text contrast for "Skip to Main Content". [#1880](https://github.com/bigcommerce/cornerstone/pull/1880)
 - Product list item Quick view button is not tabbable. [#1900](https://github.com/bigcommerce/cornerstone/pull/1900)
 - Social icon tooltip displaying should be fixed. [1907](https://github.com/bigcommerce/cornerstone/pull/1907)

assets/scss/components/foundation/alerts/_alerts.scss

@@ -15,6 +15,7 @@
 
 .alertBox--info {
     color: stencilColor("alert-color-alt");
+    background-color: stencilColor("banner--deafault-backgroundColor");
 
     .alertBox-close {
 

config.json

@@ -148,6 +148,7 @@
     "color-greyLight": "#999999",
     "color-greyLighter": "#cccccc",
     "color-greyLightest": "#e5e5e5",
+    "banner--deafault-backgroundColor": "#707070",
     "button--default-color": "#666666",
     "button--default-colorHover": "#333333",
     "button--default-colorActive": "#000000",
@@ -442,6 +443,7 @@
         "color-greyLight": "#757575",
         "color-greyLighter": "#666666",
         "color-greyLightest": "#444444",
+        "banner--deafault-backgroundColor": "#b7b4b4",
         "button--default-color": "#cccccc",
         "button--default-colorHover": "#ffffff",
         "button--default-colorActive": "#ffffff",
@@ -646,6 +648,7 @@
         "color-greyLight": "#a5a5a5",
         "color-greyLighter": "#dfdfdf",
         "color-greyLightest": "#e8e8e8",
+        "banner--deafault-backgroundColor": "#7D644A",
         "button--default-color": "#74685c",
         "button--default-colorHover": "#4f3f2f",
         "button--default-colorActive": "#917052",