Use subtitles for different Item alignments

Author: HerbertsVaadin

articles/components/flex-layout/index.adoc

@@ -138,7 +138,9 @@ include::{root}/src/main/java/com/vaadin/demo/component/flexlayout/FlexLayoutCon
 
 |===
 
-== Item Alignment (along the layout direction)
+== Item Alignment
+
+=== Along the Layout Direction
 
 You can control how items are distributed along the main layout direction (horizontally or vertically, depending on the chosen direction) by setting the content justification.
 This corresponds to the CSS `justify-content` property.
@@ -176,7 +178,7 @@ include::{root}/src/main/java/com/vaadin/demo/component/flexlayout/FlexLayoutJus
 |===
 
 
-== Item Alignment (across the layout direction)
+=== Across the Layout Direction
 
 You can control how items are aligned perpendicular to the layout direction (vertically or horizontally, opposite of the chosen direction) by setting the item alignment. This corresponds to the CSS `align-items` property.