While upgrading to J4, I've replaced several old J51 J3 templates with the J4 version of Stella. I notice that in the template typography styling, the H1 and H2 stylings are reversed. To change the colour or font of article titles I have to make the change in the Category Head colour or font. It took me a long time to figure this out (and to remember this quirk weeks later when I updated another site).