Improve layout sizing.

Review Request #7251 — Created April 24, 2015 and submitted — Latest diff uploaded

Information

student-sonar
master
2187e7e...

Reviewers

The mix of height/width-based divs and flexbox was causing some issues with
scrolling, especially when a student view was visible. These changes make
things fill the screen better.

Made my window small and scrolled around. Saw that everything that was supposed
to be full-bleed was, and that nothing scrolled oddly.