Template Manager and the related Start Center view has same
transparent highlight color as Recent Documents. Also Template
thumbnail containers should have the same size as Recent Docs view.

Change-Id: I22e417a5c5ca5a849577d5a438a193371368fe24
Reviewed-on: https://gerrit.libreoffice.org/11467Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>