Highlight title in table of contents if we're on its page

Question

I'm creating this document which has a sidebar table of contents that lists all the headings on the left of every page. I want to highlight (change color/add shading) the heading of the page we're on. For example, if we're on page 1 that has 1. Introduction, its heading in the table of contents will be highlighted in different color. Do you have any idea how to do it?

Thanks!