Email Template Table Not visible in mail

I just create a new joiners list and send it to HR. in table format. but the table border color is very light how to change that color in more visible?

Screenshot taken from Gmail

It was in table format but it’s not visible properly Please help me to change the color or how to make more.

Add this property in the table,th,tr tags

in style properties

border: 1px solid black;

<table style="border: 1px solid black;"><tr style="border: 1px solid black;">Test Row</tr></table>