Enhancement: Don't let scrollbar affect layout

Content is in the same position regardless of whether there's a vertical
scrollbar at the right (so long as JavaScript is enabled).
Enhancement: Less margin on narrow screens

The recently added space for a potential scrollbar is wider than a typical
scrollbar (it's a margin of error ...), so already provides some margin at
the right on narrow windows. The previous margin is no longer required.
Enhancement: Lace same everywhere

Don't change the lace pattern depending on whether there's a scrollbar.