Responsive product page using SCSS, BEM, Flexbox, and Vanilla JS

I struggled when it came to adding the functionality to the buttons used to change the image.

Any input on a better way to do this than the way I did is more than welcome.

Also, how do you change the color of an image e.g. from white to orange?

The "close" button on the lightbox is supposed to turn orange from white when you hover over it, but I couldn't figure out how to accomplish this.