Please check my response about how to inspect the elements and custom CSS in your ticket here: https://uxbarn.ticksy.com/ticket/3384744/

In this case, to add the borders to those elements, please try using something like this:

.portfolio-item-list .portfolio-item img,
.portfolio-category-wrapper,
.portfolio-content-wrapper {
    border: 4px solid red;
}

The code will add a 4px-thick red border to those elements.