Update to v 2 - am I missing something?

Reading the v2 documentation I understood to upgrade it was only necessary to copy the new css and js files into my existing project. Doing that loses a lot of my layout (inc header and footer toolbars; some font sizes are different as well).
Obviously I’m missing something and will be grateful for some guidance on updating to Version 2.

It doesn’t say that it just enough to replace JS/CSS files. There are a lot of changes in v2. Migration guide to v2 will be by the of this week

OK, will will wait for that to appear.