Styles from header view not being applied

Hi all. I've used CI3 over the years, just now getting into CI4. Following the User Guide instructions exactly, in the Build Your First Application, News section, the only thing different I did was add a style sheet in the header view. When displaying all news items (overview) the styles are applied to the finished presented page. But when choosing an individual news item, the styles are not applied. The title is grabbed and applied, but not the styles. What would be causing this and how should I resolve this issue?  Thank you.