Defines the borders for this cell -- these definitions override the definitions given by the table borders.
      
        | Element | Description | 
      
        | top | Defines the top border of the cell. | 
      
        | left | Defines the left border of the cell. | 
      
        | bottom | Defines the bottom border of the cell. | 
      
        | right | Defines the right border of the cell. | 
      
        | insideH | Represents the horizontal border between two cells. Only used in table-style conditional formatting. | 
      
        | insideV | Represents the vertical border between two cells. Only used in table-style conditional formatting. | 
      
        | tl2br | Defines the top-left to bottom-right diagonal border of the cell. | 
      
        | tr2bl | Defines the top-left to bottom-right diagonal border of the cell. | 
    
None.