D11922: Wallpaper templates: set background color to ensure contrast to sample text content

[Marco Martin]

mart accepted this revision.
This revision is now accepted and ready to land.

REPOSITORY
  R242 Plasma Framework (Library)

BRANCH
  improvetemplateswithbackground

REVISION DETAIL
  https://phabricator.kde.org/D11922

To: kossebau, #plasma, mart
Cc: #frameworks, michaelh, ngraham