Minor design improvements and hint for unpublished polls

[dartcafe]

Some minor UX issues:

• Give a hint, if the poll is not accesiable from anyone else but the owner.
• Unify the width of date polls, to be able to better differentiate between the poll options
• Introduce text-wrap: balance; for text polls (Not supported by all browsers)
  See https://caniuse.com/css-text-wrap-balance
• fix sidebar tab change

Hint for unpublished polls and unified column width