Test on theme Boost only, in these testing instructions you will add a background image so this change becomes more visible. Log in as admin. Navigate to Site Administration > Appearance > Themes > Boost. Add a background image (sample provided in this issue). Navigate to your dashboard. Click customise this page. Move a block from the right-hand column to the center column. Verify the blocks appear to float in the center column (this means you should see the background image in between each block) Verify there is no extra padding, white background or border around the centre blocks.