Custom CSS/JS is not available in the horizontal template to ensure ... In the Page Properties dialogue box, click on the Advanced tab. Click on the arrow next to "Custom Stylesheets and Javascript".

Using this power for visual elements does however make a lot of sense considering that CSS was always intended to help with styling and formatting the raw HTML. Do you use these advanced CSS ...

Learn React & CSS by reverse-engineering Facebook's new multi-level dropdown UI in this beginner-friendly tutorial ...