Fix sidebar layout scrollbar with absolute positioning.
Remove explicit height (and calc function) from .sidebar-content to make css more DRY and sidebar rendering more consistent across browsers.
Move .sidebar-header border-bottom to a border-top on .new-map .sidebar-content so that it only shows up on the /maps/new page.
Remove explicit height from .sidebar-header.  Fix navbar dropdown override.  Add comments to CSS.
Wrap title in <h3> element in show.html.erb.
Add padding to the bottom of the "Create Map" button.