You’d be far better off moving to CC which does a far superior job exporting to EPUB. I’ve done them with no need to write any CSS or crack open the EPUB.
With CS6 you’re going to need to do both.
The value in td, th is the default value. You should not be concerned with that..
This value can be overridden by the cell style, cell overrides or by table styles that you have applied on the table in InDesign.
For your case where you want a table with all cell borders=0px.
I would suggest create a cell style say "zeroborder" with cell border= 0px. Create a table style "T1" with table border=0px and cell style(in table style panel at general pane) "zeroborder".
Apply this T1 style to the table and you shall have the desired results on export..
Let me know if it works for you..
Thanks for replying. I think the problem is in InDesign CS6. I did try Monica's suggestion, but I still get the 1pt border around the cells and table border when I export to ePUB. Both of my table and cell styles have zero set to the stroke weight. However, if you notice in the CSS I posted, there is no border-width for 3 styles I used (table.Table-Four-Rows, td.Table-Header-row and td.Table-Body-Row-Spacing).
I took Bob's advice today and downloaded the CC 2015 version of InDesign and exported the very same file without making any changes to it. This time, when I exported to ePUB, there were no borders, like I wanted. I've found that tables in CS6 don't always display the settings I'd define in a table or cell style.
A big thanks for both of your suggestions!