Table header cells should be vertically aligned in the middle, not at the top.

	Foo bar

Expected results: The middle of the text "Foo bar" should be lined up at 100px, not at the top.

Reference: valign middle: Cell data is centered vertically within the cell. This is the default value.
coming from HTML 4.01, section 11.3.2, Horizontal and vertical alignment for table cells, valign attribute