Hello @CassieL32 ,
I can at lest provide a bit of technical insight. The standard builder uses a block system to construct emails, using our proprietary coding that's been setup to work within the set limitations for a more simple, straightforward email building experience. Custom code is fully dependent on the code you provide for pretty much all of its elements. It's like the difference between building a house with pre-constructed walls, pipes, and wires on a plot of land VS. making your own bricks, harvesting your own lumber, and forging piping and an electric system to freehand-build a house.
Certain pre-built templates will contain specially-coded elements from the Design team that cannot be replicated in the general builder. This can range from very specific layout block setups to graphical elements like background images/patterns.
The Feature Article layout block is specifically setup to not stretch the full width, since it's supposed to appear as a floating section in a larger newsletter, with a differently shaded background to help it stand out. Another comparison - think of textbooks that have the small pop-out areas with an image and additional context of the image. If you're wanting to have something like the Feature Article layout with its background stretched the full width, you can just do that with the Article layout, and change the background color for that row.
For additional info and guidance on layout blocks, background coloring, and building your email in general, I'd advise referring to the following articles (also available via the Help tab in your account):
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William A
Community & Social Media Support