Questiong regarding Customize CSS

Overriding CSS code to customize the appearance of h1, h2, ... does not seem to be working.

![Image](https://github.com/user-attachments/assets/9eaee87d-da24-4563-ad07-66ef1ca4d209)



```
#+SETUPFILE: https://fniessen.github.io/org-html-themes/org/theme-readtheorg.setup
#+HTML_HEAD: <style> h1, h2, h3, h4, h5, h6 { margin-top: 2em; } </style>
```
