I'd like to be able to edit and/or move some elements of the Cascade map I'm working on.
You have the ability to download the source code for the app and you could then host it on your own web server. You could then customize the application framework as much as you want. But, if you want the application to still remain hosted in ArcGIS Online or your Portal, beyond some of the CSS and style overrides, you cannot apply wholesale changes to the application.
Great Resource: https://developerscorner.storymaps.arcgis.com/
For more info and an introduction to what you can do, see the 'If You're a Developer' section on the Story Maps Resources page: Resources | Story Maps
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