I inherited this site: http://www.thinkiam.com/
It's WordPress using Slider Revolution.
The default full size of the slider & it's images is 1200p. When the screen is smaller than that, the prior slide zooms in just before the next slide loads.
And the only reason the slides initial load at the right size is because I added background-size: cover to them. Without that style, the images are not responding even when they first appear.
You can see that by inspecting and turning this off
@media screen and (max-width: 1200px)
style.css?ver=1.0.0:27
div.tp-bgimg.defaultimg, div.slot {
background-size: cover;
}
What settings in Slider Revolution that will produce a simple responsive slider?