This block is for headline block that has three type. "Headline 1" output <H1> tag with style attribute. Also "Headline 2" outputs <H2> tag, "Headline 3" outputs <H3> tag.
Add or Edit window that has "Create" tab and "Setup" tab. The "Create" tab choose kind of headline type and headline text before "Save" buton. Output tag, H1, H2 or H3, has "CSS of headline" as style attribute.
You can change each default CSS. So "Setup" tab keeps each default CSS.