Remove borders from tables on EPUB export

Hi, I'm trying to create a document with poetry lines on the left side of the page, and line numbers on the right side. The problem is that with reflowable EPUBs, larger font sizes make the single lines span multiple lines, and the line numbers no longer match.

The solution I've hit upon is to use tables. This has worked perfectly, see below:

And with larger font:

The problem is the borders you can see in the tables. The above are EPUB screenshots, I've set the table in InDesign to have no borders:

How do I remove the borders in the EPUB?

I've been told that I can do this only by editing the CSS. I've attached a sample EPUB because I can't find where the table border is when I open it up in Sigil.

Thanks in advance for your help.