The title and submit frames showing scroll bars can have the html body tag scroll="no"
<body scroll="no">
so irrespective of a frame or normal rendering, there would be no scrollbar.
What you're seeing is how Safari draws scrollbars when there is not enough space to draw the entire scrollbar widget set. You should set overflow: hidden in the CSS for the body of any frame/page you don't want to scroll. Note that Safari doesn't entirely obey these rules (or scroll="no" on the element) in that you can actually scroll the element by drag-selecting its contents, if there is in fact content beyond the visible area.