Why Did My Post Column Move So It’s Not Next to My Sidebar Anymore?
If your post column has moved so you have to scroll down to the bottom of your sidebar to see it (or vice versa), an element in your post column (or sidebar) is too wide. For example, if an image file is wider than the width of your post column or sidebar, as defined in your theme’s style.css
file, it will push the content in the columns next to it out of the way so it can fit. The column(s) that gets pushed out of the way has to go somewhere. Usually, it ends up appearing at the bottom of the column with the too-wide image. You have to scroll down to see the missing column(s).
If you use Mozilla Firefox as your web browser, you can easily check the width of your blog’s columns ...