Various improvements

- Corrected class name
- Made selectable item width slightly wider for desktop view
- Changed colours to show disabled states correctly
- Included correct and incorrect colours
- Fixed issue where selectable items had a fixed width when changed to
small and medium devices
- Fixed bug where IE changed disabled selects to a grey font colour,
making it unreadable.

--- NOTE ---
More work might be required on the way the select is working, however
this fix is must better than previous version.