Bug 27631: (follow-up) Modify logo CSS to give better alignment

Bug 27631: (follow-up) Modify logo CSS to give better alignment

This patch modifies the CSS of the Koha logo and its container so that
it more closely matches the previous version and so that alignment is
handled better at various browser widths.

To test, apply the patch and build the staff interface CSS
(https://wiki.koha-community.org/wiki/Working_with_SCSS_in_the_OPAC_and_staff_client).

Check various pages in the staff interface to confirm that the position
of the Koha logo is correct. Adjust your browser width to confirm that
the alignment adapts at narrow widths.

Test also on pages where the header search form can be expanded, e.g.
Patrons -> [+] to expand search options. Or Acquisitions -> Orders
search -> [+]. Confirm that logo alignment is correct on these pages
too.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>