user: Question: For which Category was Outstanding Main Title Design a Recipient and nominee?
Columns: ['Year', 'Category', 'Recipients and nominees', 'Role/Episode', 'Result']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [2006.0, 'Outstanding Casting – Drama Series', 'Libby Goldstein and Junie Lowry-Johnson', 'Libby Goldstein and Junie Lowry-Johnson', 'Nominated']
SQL:

assistant: SELECT "Category" FROM "Table" WHERE "Recipients and nominees" = 'Outstanding Main Title Design';