Remove grey background from .content-wrapper

- Fixes #9667

CHANGELOG.txt

@@ -42,6 +42,7 @@ Changelog
  * Fix: Allow reviewing or reverting to a Page's initial revision (Andy Chosak)
  * Fix: Allow both horizontal and vertical manual resizing of TextFields (Anisha Singh)
  * Fix: Use the correct padding for autocomplete block picker (Umar Farouk Yunusa)
+ * Fix: Ensure that short content pages (such as editing snippets) do not show an inconsistent background (Sage Abdullah)
  * Docs: Add custom permissions section to permissions documentation page (Dan Hayden)
  * Docs: Add documentation for how to get started with contributing translations for the Wagtail admin (Ogunbanjo Oluwadamilare)
  * Docs: Officially recommend `fnm` over `nvm` in development documentation (LB (Ben) Johnston)

client/scss/components/_grid.legacy.scss

@@ -34,7 +34,6 @@
   height: 100%; // this has no effect on desktop, but on mobile it helps aesthetics of menu popout action
   float: left;
   position: relative;
-  background-color: $color-grey-4;
   border-bottom: 1px solid $color-grey-3;
 }
 
@@ -53,7 +52,6 @@
 @include media-breakpoint-up(sm) {
   .content {
     border-top: 0;
-    background-color: none;
     padding-top: 0;
   }
 }

docs/releases/4.2.md

@@ -54,6 +54,7 @@ depth: 1
  * Allow reviewing or reverting to a Page's initial revision (Andy Chosak)
  * Allow both horizontal and vertical manual resizing of TextFields (Anisha Singh)
  * Use the correct padding for autocomplete block picker (Umar Farouk Yunusa)
+ * Ensure that short content pages (such as editing snippets) do not show an inconsistent background (Sage Abdullah)
 
 ### Documentation