Fix calendar selector in 'Datetime' widget in search content view

When using a Datetime widget with BETWEEN operator in the search layout of a search content view, the date selector is partially hidden:

How to reproduce:

• create a new content view
• check search content view box
• Drag&Drop dc:created field in the search layout:
  • select Datetime widget
  • select BETWEEN operator
• define columns in Results tab
• deploy
• log in the JSF UI
• go to the SEARCH main tab and select the new search content view
• click on the claendar icon next to the to input field

Expected result: the calendar selctor is rendered properly
Actual result: the calendar selctor is partially hidden by the right panel