Limitations of Customizing the latest Twenty Seventeen Theme

The latest Twenty Seventeen theme is beautiful and fun to work with. But it seems to have limitation of customization. I don’t see any css for columns in the stylesheet, or maybe I am just overlooking it. And trying to reduce the height of the footer with css isn’t working or it’s not clear how to easily do this. Also when I try to put the footer widgets items (for example address, footer navigation and social media icons) in a column, it’s not obvious to me how to easily do this.

Otherwise it’s a great theme and fun to work with.