Required File Structure
From Website Builder
When finished, a website builder theme should be a ZIP file made up of the following:
This is the required file structure for a website builder theme.
The file structure of a website builder theme is slightly different than you might be used to working with. The theme file itself should always be named default.html and any assets - images, js, css files, etc. should be placed in the /assets/ directory. You can place sub-directories into the /assets/ directory if you want to organize your files better.