It is not possible to add custom JavaScript to a WordPress site. As for CSS, you can add inline styles to the HTML.
To add custom CSS to a page, you can go to Dashboard > Appearance > Additional CSS. Any custom CSS added here will affect styling across your whole site:
![advanced options for page](https://teamdynamix.umich.edu/TDPortal/Images/Viewer?fileName=083e0bc8-5ac7-41df-8a43-ac34601a1e11.png)
You can also add additional CSS classes to individual blocks. When you are editing a block, expand the Advanced settings dropdown in the block settings panel. Enter the desired CSS classes in the text box labeled “Additional CSS class(es).”