There are many blog posts about increasing / decreasing header footer area in blogger but I hardly found any article about how to increase main content post section, so I tried a lot of things & finally found the solution.
Here is how to do it,
Go to Template > Advanced > Scroll down to Add CSS
Type the following
.content-inner { min-width: 1040px; }
and save it. You can adjust the width as per your wish.
