I see that you have a table creating a grid of images, but there is no border on that table.
Using my browser inspector I find that the double line lime green border is on a div element with a class of “page-holder”, the style is:
border: 6px double #33ff00;
To change it you can:
– login to your WordPress admin dashboard
– navigate to your “roster” page
– on the top edge select “customizer” then click on the additional css tab.
– add a phrase like this:

.page-holder {
 border: 1px single #33ff00;
}

Or whatever border style you want.