Wide, Full Width or Boxed Layout?
Please select, which Layout variant you prefer. With the Wide Layout you can create sections, where you will not see the left or right border of the content. There is only one Background, though the content width is limited to 1200 px.
With Wide Layout you can create sections, which will fill the complete browser width on large screens. These Full Width sections can only have a background filling the complete width and the content itself is in the boundaries of 1200 px, or the content itself fills the complete browser width.
A last option for Full Width is to have no space between the columns. This might be useful, if you want to load any images beneath each other.
If you prefer the boxed Layout you will see an extra background on both sides of the content area. You can fill this background with an image or with a color, or you can have a color mixed with semitransparent tiles, selected at the Options panel.