collapse is supported by Explorer Mac, Mozilla, Opera and Safari, but it gives the same effect as hidden.

The visible and hidden values of the visibility declaration are well supported. In CSS2 visibility has a third value: collapse.

visibility: collapse exists only for table rows and columns and means: remove the row or column entirely (as display: none does, too), but do not recalculate the widths and heights of the TD's in the other rows.

Unfortunately this value is not at all supported, all browsers render it as visibility: hidden.

This is the test table. It has three rows and two columns
This is the test TR. visibility: collapse should make it invisible, although it still counts for the calculation of the widths of the TD's in the other rows  
Change the visibility of the test row: visible
Change the display of the test row: block