Remove unnecessary mixin

seedlet/assets/sass/abstracts/_mixins.scss

@@ -113,23 +113,3 @@
 		 }
 	 }
  }
-
- @mixin innerblock-margin-clear($container) {
-
-	 // Clear the top margin for the first-child.
-	 > #{$container} > *:first-child {
-		 margin-top: 0;
-	 }
-
-	 // Last child that is not the appender.
-	 > #{$container} > *:last-child:not(.block-list-appender) {
-		 margin-bottom: 0;
-	 }
-
-	 // When selected, the last item becomes the second last because of the appender.
-	 &.has-child-selected > #{$container} > *:nth-last-child(2),
-	 &.is-selected > #{$container} > *:nth-last-child(2) {
-		 margin-bottom: 0;
-	 }
-
- }

seedlet/assets/sass/blocks/cover/_editor.scss

@@ -6,8 +6,6 @@
 	margin-top: inherit;
 	margin-bottom: inherit;
 
-	@include innerblock-margin-clear(".wp-block-column");
-
 	.wp-block-cover__inner-container,
 	.wp-block-cover-image-text,
 	.wp-block-cover-text,