Fullscreen Slider – Image Alignment with max height

Hi,
I have used your theme for many sites, much appreciation!

For a particular website I have set a maximum height on the slider because i use a lot of images with different sizes on different pages. I used this code (found on the forum) te set the height:

@media only screen and (min-width: 1200px) {
 .avia-slideshow-inner {
height: 500px !important;
}
.avia-slideshow {
max-height: 600px !important;
}
}

This works without a problem, but for most pictures it now only displays the top part of the image. therefore i am trying to set the image alignment for all images to ‘center center’ or ‘bottom center’. Unfortunately the code i have found on the forum here no longer seems to work:

.avia-fullscreen-slider .avia-slideshow-inner li {
background-position: center center !important;
}

Hope you can help me to correct this! :)

Mauro