How to avoid double border in WYSIWYG

I am using PDF template module to build table, but the table cells always come with double border, what HTML code should I write to get rid of this.
I tried style=“border:?” in

or it does not work

I don’t want double border…

When you click on the table icon in the wysiwyg editor, is the border field set to 0?

The border field can be set to 1, but I forgot to put “border-collapse: collapse;” in the

. Now it works. Thank you