What is Site Size?
Site size means maximum width of your content in a big enough monitor and sidebars width in it. Publisher makes it very easy and user friendly to resize site width, columns size and the gap between them. Go to Publisher → General → Site Width, here you can resize your “two column” and “three column” layouts simply by sliding columns.
How to Change Columns Width?
As you see in above image, “two column” and “three column” layouts have their own sizing. Just grab handlers and resize them to desired pixel. Use internal handlers to change every column size in percentage of the total width.
NOTE: In “three column” layout, the “Sidebar 2” will be removed in screen sizes between 1000px and 768px and screens smaller than 500px.
You can use different layouts for different pages in Publisher (2 column or 3 column). Every layout uses its own sizing. For example your homepage is “three column” layout with a total width of 1300px, and posts use “two column” layout with total width of 1200px, then your website homepage looks different from posts.
How to Change the Gap Between Columns?
See image above, change Columns Gap to your desired number (in pixels). This gap is both vertically and horizontally.
NOTE: Big gap may ruin your style; Your content layout might seem visually inappropriate, specially when the width of device is smaller than the site maximum width.