2.2.59 [CSS-Level2-2009] Section 17.5.3, Table height algorithms
The specification states:
The height of a table is given by the 'height' property for the 'table' or 'inline- table' element. A value of 'auto' means that the height is the sum of the row heights plus any cell spacing or borders. Any other value is treated as a minimum height. CSS 2.1 does not define how extra space is distributed when the 'height' property causes the table to be taller than it otherwise would be. Note. Future updates of CSS may specify this further.
Quirks Mode and IE7 Mode (All Versions)
The border-spacing property is not supported, so if the table includes border spacing, the height is not incorporated into the table height. Borders are spaced 1px apart.