Improve card contrast by changing the background from white to grey

[jmaferreira]

These improvements could also be applied to DBPTK.

Change the background of the main content from white to grey

Make the page header full width

Add margin to the cards so that they don't stick to the sides of the page

Make the new tab button similar to the other buttons on the toolbar

Check all the other pages for inconsistencies

[hmiguim]

No resources available to take on this tasks and redesign every page in RODA to be consistent. Move to next major release RODA 6.