fix typo mixins

assets/sass/_theme/design-system/typography.sass

@@ -159,11 +159,18 @@ p
 small, .small
     @include small
 
+
+@mixin rich-text
+    h1, h2, h3, h4, h5, h6, p
+        margin-top: 2em
+    &:first-child, meta + &
+        margin-top: 0
+
+.rich-text
+    @include rich-text
+
 [itemprop="articleBody"]
-    h1, h2, h3, h4, h5, h6
-        margin-block-start: 2em
-        &:first-child, meta + &
-            margin-block-start: 0
+    @include rich-text
 
 @mixin blockquote
     margin: 0