Don't use shadow border

frontend/src/assets/scss/elementStyles.scss

@@ -206,8 +206,7 @@ b, strong {
 		padding: 1.5rem;
 		border-radius: 0.25rem;
 		margin-bottom: 1rem;
-
-		@extend .shadow_border;
+		border: thin solid $color__gray--darker;
 	}
 
 	@at-root #{&}__text {

frontend/src/components/routes/AdminModerationBannedUsers.vue

@@ -258,7 +258,7 @@
 			border-radius: 0.25rem;
 			border-collapse: collapse;
 
-			@extend .shadow_border;
+			border: thin solid $color__gray--darker;
 			
 			td, th {
 				padding: 0.5rem;

frontend/src/components/routes/AdminModerationReports.vue

@@ -194,7 +194,7 @@
 
 		@at-root #{&}__reports {
 			margin-top: 1rem;
-			@extend .shadow_border;
+			border: thin solid $color__gray--darker;
 
 			border-radius: 0.25rem;
 			&> :first-child {