Thank you, that worked for pages.
As for posts, I wonder if modifying the php would be easier? I hate fighting CSS…
EDIT: Found the CSS that worked for me:
I have dual sidebars, surrounding the content. So I need to suppress both.
Code:
.single-post #content-main {
width: 100%;
}
.single-post #sidebar1 {
display: none;
}
.single-post #sidebar2 {
display: none;
}