Bug 34129: Fix plus and minus icon

Bug 34129: Fix plus and minus icon

This patch fixes the plus and minus on the buttons to expand the columns
in mobile or zoomed in view.

To test:
1. Apply the patch
2. Rebuild css (yarn build)
3. Go to the OPAC and search for a record with an item
4. Zoom in to 400% or change view to mobile
--> The items table should have a plus (+) button in the last column to
expand and have the rest of the information

Signed-off-by: Caroline Cyr La Rose <caroline.cyr-la-rose@inlibro.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>