We are considering the Learn 2016 Theme in Q4 2016. For banner customization I noticed the following:
1. Navigation Settings -> Banner Image
This item works well. Any size logo is scaled to the height of the frame and renders correctly.
Quick links appear outside of the main canvas, perhaps that's on purpose, but it doesn't feel right.
2. Customize Colors -> Top Frame, Background Image
Once a background image is applied, the remove button disappears. This means you have to clear all customization (Reset Custom Colors) at the bottom and start over.
Please post any other technical specs you reverse-engineer.
The size of this image is problematic. It will auto-repeat horizontally and vertically. I found that creating image size 1300px by 152px provides a wide enough banner to match frame size. Also, 152px height will cut about 25% from top and bottom, but as long as you use the middle of the image for artwork, it will render correctly.
If you can, please upload any sample banners you developed or tricks.