Add border around image shape in FE

I'm using FE and cant find the CSS to add a border around an image block that uses a shape.

To add a border to an original image (one that hasnt been adjusted with the "shape" option), I use the code below and make sure the image is in "fill" mode. You have to adjust/size the block to fit the image but it seems to work.

#block-yui_3_17_2_1_1668125166103_10204{
    border: 3px solid black;
}

But when I switch the same square image to a round "shape", the border stays square as you can see below. Im obviously missing something. Can anyone help?

Please see the following.

Thank you Creedon, i read the thread you attached. What an odd thing for SS to throw out/not address. Hopefully, the ability to add a simple border to a chosen photo shape will be part of the program soon -whether you code the shape or use one of the in house options.