Header No Longer Responsive

Hi! For some reason the header image on my website is no longer responsive between desktop and mobile devices —?on smaller screens the image is simply cut-off.

I can’t find any sort of toggle on the customization screens to “turn on” responsiveness. Is it something in my CSS?

I made sure to upload an image that is exactly the size recommended by the Treeson theme.

My website is https://www.theheartofhappy.com

Thanks in advance!