I am currently working on a new theme for Moodle 3.6 which I am basing on the CLASSIC theme layout that Bas Brands is getting ready for the launch of Moodle 3.6.
At the moment it looks very much like the Clean theme so I may end up up-dating my MORECANDY theme for 3.6 based on the Classic layout too.
It's looking good so far, and I have got over some odd problems that, in the end, where of my own making!
That said, I have come across a couple of small issues that I would like to fix, which relates to the size of some of the Font-Awesome icons, such as "area-chart" and other navicons found in Moodle which appear to be bigger than the rest.
So if you have noticed the same with chart icons, then try adding the following SCSS to the Advanced > Raw SCSS settings area of the Boost theme, it should fix it