Add basic column widths for 1200px layout
Correct column widths for 1200px layout"
Add basic column widths for 720px layout
Add basic column widths for 480px layout
Add basic column widths for 240px layout
Merge branch '720px'

Adding 720px viewport to master
Merge branch '480px'

Adding 480px viewport to master
Merge branch '240px'

Adding 240px viewport to master
Add basic layout demonstration