Recently I have been having issues with Outlook 2016 for PC not sizing images down as the preview pane gets smaller. I have been using this css on my images...

.img-max {
        width: 100% !important;
        max-width: 100% !important;
        height: auto !important;

...but this no longer works. It, of course, works in Outlook 2016 for Mac, but on PC images will not scale and it breaks the layout. I pulled out the image and the email was fine, all the text was wrapping as window got smaller, so I know it has to be the image. I did some research and found nothing that worked. So I took the code from a recent Litmus email and tested that, since Litmus emails are the best example of a responsive email...but the same issue was happening in Outlook on PC. Has anyone else been having this issue or know how to fix it?