Add a clear div and change mixed spaces/tabs to tabs

Cosmetic fixes to code and a clear div to allow content to be
added below SketchPads.
Change page title from h3 tag to h2 tag

Page title looks best with margin-top: 0
Add HTML file for test cases

Added this file, because it may be best to leave index.html as a clean,
working boilerplate, and run tests here.