Rewrite styles to scss and use i respective components

src/components/HeadlineGroup/HeadlineGroup.tsx

@@ -0,0 +1,6 @@
+import React from 'react';
+import classNames from 'classnames';
+import './headline-group.scss';
+export default function ({ children, secondary = false }: React.PropsWithChildren<{ secondary?: boolean }>) {
+  return <div className={classNames('headline-group', { 'headline-group--secondary': secondary })}>{children}</div>;
+}