i element for icon

I am doing an accessibility audit of our website using https://achecker.ca/checker/ and 43 of the known problems that come up are all related to the popups on our Virtual Career Guide on our site and appear to be how the i element is used. It states that the <i class=”spu-icon spu-icon close”>() should be replaced with em or strong. I’m thinking span should also work. I’m not sure where to update this or if there is a CSS code I can use. Can you help with this?

Any help is appreciated. Thanks!

The page I need help with: [log in to see the link]