Add additional padding/margin around ReportView when in Wide Mode.

Dev notes:

• Sadly not as simple as `if widemode, left/right padding = 5rem", for two reasons:
  • ReportView is used by the Sidebar as well, and we don't want to increase padding there
  • On mobile, we presumably don't want to add padding on left and right modes
• Tried using max-width: calc(100% - 10rem) but that still runs afoul of the mobile and sidebar issues.