Bug 14190: Scale search boxes in staff head

Bug 14190: Scale search boxes in staff head

In this simple patch the width gets controlled by CSS and it becomes
easy to set it in just one place.

The exact width may need to be discussed but I thought 30em made it look ok on my screen.
With this patch we get the wider search boxes with a very small change and another bug may
be created if needed to do a bigger refactor and remove stuff not needed in the html and
perhaps do this in a modern/responsive way. (Preferrably a UX/GUI developer will do this)

To test:

Apply the patch and reload the staff client. Now the search box is a bit wider and the border
etc has changed with it.

Some places with more than one search box like "Serials" will not be affected.

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>