Bug 30190: Green buttons turn blue for a second when clicking them

Bug 30190: Green buttons turn blue for a second when clicking them

This patch adds additional CSS to better cover various states of buttons
in the OPAC.

To test, apply the patch and rebuild the OPAC CSS:
https://wiki.koha-community.org/wiki/Working_with_SCSS_in_the_OPAC_and_staff_client

- In the OPAC, test various green buttons in varous states: default,
  hover, and active (the appearance when the button is clicked but
  before the mouse button is released).
- The button should be styled in various shades of green in all cases.
- Test a disabled button by performing a catalog search.
- On the results page, before any checkboxes are checked, the "Save"
  button should look correct.

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>