I have a website I’ve made for a pet sitting company. The interior pages are single column but I would like to have the sidebar appear on the Blog posts. The problem I’m having is that the interior pages being single column need to have a width of 960px but on the blog posts i need to have a smaller width to allow room for the sidebar. Right now it is being pushed underneath the copy.
I have done this, one way to do it, not saying it is the best way but it has always worked for me.
Modify your single.php page, add the get_sidebar call to add the sidebar and rename your content id to something like singlepagecontent, so you can style the width of the content so you can fit the width of the sidebar and get them side by side.