fix: styles empty version diff row for dark mode

src/admin/components/forms/field-types/Tabs/index.scss

@@ -13,9 +13,7 @@
   }
 
   &--within-collapsible {
-    margin-left: calc(#{$baseline} * -1);
-    margin-right: calc(#{$baseline} * -1);
-    margin-bottom: 0;
+    margin: 0 calc(#{$baseline} * -1);
 
     .tabs-field__tabs,
     .tabs-field__content-wrap {

src/admin/components/views/Version/RenderFieldsToDiff/fields/styles.ts

@@ -8,6 +8,7 @@ export const diffStyles = {
       removedColor: 'var(--theme-error-900)',
       wordAddedBackground: 'var(--theme-success-200)',
       wordRemovedBackground: 'var(--theme-error-200)',
+      emptyLineBackground: 'var(--theme-elevation-50)',
     },
   },
 };