hgweb: use css margin instead of empty <p> before <div class="atom-logo"> The <p> elements were used to create an empty space between the last menu item (i.e. "help") and the atom feed icon, but they don't have any semantic meaning, so it is better to use css instead. The css rule uses top margin of 10px, which is equal to the top margin of the menu blocks ("help", "changeset, browse", etc). Previously, with <p> elements, the margin wasn't set explicitly and was browser-dependent. This change is a "better version" of 70cfa7e1611b, where <p> elements were simply properly closed.