Thanks for the feedback! The interesting thing about the CSS grid is that the cells are not actual empty elements, but we want to represent the cells visually somehow to help with affordance. We'll be adding some much needed enhancements to the copy-paste interaction (I mean, it's so fundamental) soon, like giving you the ability to select these non-existent cells so that you can paste inside of them. Let us know if there's anything else that can be improved.

The next big release will include grids with contents that auto-flow vs having to always manually position them.