FAQ accordion card using HTML, CSS and JavaScript

I found the accordion fairly easy to implement and also making a single accordion expand at a time. However i found it difficult (couldn't figure it out at all) to add/remove the active class on the accordion button so that the font weight/arrow direction would be correct when the panel would shrink once another button/question was clicked. The class is added and removed when a button is selected then that same button is selected again but doesn't work if another button is selected.

I also couldn't figure out how to have the left portion of the main image(woman online) to be behind the background.

I also struggled a little getting this to be mobile responsive.