Make sure that the width of the element is set to 100%, which will allow for fluid movement.
The images can either be a fixed width, which will drop down lines with browser window scalling, or you can set the images to have a width of 100% for mobile CSS. A general example would be as follows with 490px representing mobile view.
@media (max-width:490px) {
.yourdiv img {
width:100%
}
}