Full width easy slider height change

When I apply the css in https://kriesi.at/support/topic/full-width-easy-slider-cutting-off-content-narrow-image/ to make my full width easy slider 530px instead of 430px or 630px, it works to the extent that the slider is indeed 530px high and I’ve been able to adjust the ratio of my images to avoid image distortion to:

.avia-slideshow li img {
height: 530px;
width: 1262px;
max-width: 1262px;
}

However, I seem to lose the “stretch to full width” feature with this as so I’m seeing the background slide colour on either side of my image. How can I set the slider height to 530px without distortion and without losing the full width feature?

Thanks,
Louise