Refactor styles

- set fire to old css
- write new css for refactored html (see 'search-accessibility-fixes'
branch of alphagov/frontend)
Apply display block, stop whitespace interferance
Use padding instead of text-indent

Unfortunately using text-indent was causing style weirdness, where the cursor for the search box was appearing below the search box, resulting in "wait, wat?"-ness.
IE6 transparency fix
IE6 fixed height fix
Deal with lack of support for box-sizing

Also add dimension for IE
Box-sizing retained for IE6
Merge pull request #240 from alphagov/search-accessibility-fixes

Search accessibility fixes