I am interested editing the HTML/CSS and I see that its not possible without hosting the code or using Journal. All the information I found has been from past years, so I am asking in case there was an update to these questions with newer versions of ArcGIS online.
Thank you!
Hi Vera -- For security reasons, there's no way to directly edit the code of a story hosted on ArcGIS Online. You'll have to download and host the code yourself to have that kind of freedom—and in that case you accept all the risk for whatever modifications you make.
All the permitted customizations for stories hosted on ArcGIS Online are documented on our Developers' Corner blog; you can check those out here: https://medium.com/story-maps-developers-corner
Owen