chapter: tiny fix

assets/sass/_theme/blocks/base.sass

@@ -34,6 +34,12 @@ $backgrounded_blocks: ".block-call_to_action, .block-chapter--accent_background,
 .heading + .block-chapter
     margin-top: $spacing1
 
+// Following chapters
+.block-chapter
+    &--alt_background, &--accent_background
+        & + &
+            margin-top: 0
+
 // Heading + block_cta + full-width
 // .heading + .block-call_to_action
 //     margin-top: $spacing3