Hi guys! Jo here! I've never really explained the concept for the Aikatsu and Aikatsu Stars userboxes, so I'll talk about it along with the release of the new userboxes for Koharu, Ako and Mahiru.
For the Ichigo generation characters, the info section takes on a lighter shade of the idol's theme color, while the border uses a darker shade. So basically, its a one color, two shade thing.
As for Akari Generation, the concept is slightly different: using the Parade coords as inspiration, while the info section uses the idol's main theme color, the border uses the parade coord/idol's second color.
Aikatsu Stars! Gen
As for the Aikatsu Stars! Gen, we (I) take on a whole new different concept. I debated for some time if I should leave the image background white, but since the idol images come with the border, I thought of trying something else.
And so, the info area and image background color corresponds to the idol's hair color, and the box border color is the same (well, as same as possible) as the idol image's border color.
And the new userboxes that we have since 12 July, 2016....
Enjoy your day!