[ticket/12562] Add max-width to proSilver

PHPBB3-12562
Merge remote-tracking branch 'PayBas/ticket/12562' into develop-ascraeus

* PayBas/ticket/12562:
  [ticket/12562] Add max-width to proSilver
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/12562] Add max-width to proSilver