I have cells that are 23 pixels high, and I need cells that are 8 pixels
If the cells that are 23px tall have content that is driving them to be 23px
tall, then you will not be able to size any other cells in the same row to
be shorter than 23px. The solution would be to merge the cells that you
want to be shorter, and nest a new table within that merged group, and have
the nested table's cells forced to the desired height.
It seems like that there
is a minumin height set that will not let it go below 19 pixels.
19 px is the height of an unstyled character. That character is
automatically placed into all cells of a newly created table to prevent the
browser from seeing them as empty cells (which will not render with borders
or background colors). What you are seeing is the effect of those
non-breaking spaces. When you insert an image, the is automatically
replaced by the image. This will allow you to "shim" the cell to any
dimension by adjusting the width and height of the transparent GIF image as
needed.