HTML Widgets; Accounts Breakdown; Table styles moved into widget.css

The format of the report tables used in the "Accounts Breakdown" HTML Widget have been tweaked and moved out of the Script's Template Text and into the widgets.css which is shared by all Widgets.

This allows consistency going forward and has a new "is-widget-report" class that can be added to tables (generally those with the "is-grid" class already applied) and updated centrally.