Refs #2567: add 800px wide wrapper for newsletter tables
Refs #2567: remove table borders that come from admin theme
Refs #2567: uniform class selectors for horizontal blue lines in header
Refs #2567: zero padding for blue-line table cells
Refs #2567: proper height for newsletter title and issue_number on admin interface
Refs #2567: correct padding and margin for tables of newsletter preview on admin interface