layouting

Previously, when the pages had a height
smaller than the screen's height,
the footer was displayed somewhere in the
middle of the page.

Display the footer at the bottom, with
no whitespace after it.

- Make footer full width and put it at the bottom.
- Replace light blue bar below the navbar
  with white bar, to match the bar above the footer.

Make the "Search" button fit in more with
the other navbar items.