Hi Peter

I think what you are referring to is the cropping current image viewport vs original aspect ratio

My fullscreen parallax image is not responsive and does not scale well

Hey Peter,

Ok I see what you mean.

The width is set in slider's javascript initialization. To force it to a certain height you could add

.owl-carousel .owl-item {
    max-height: 300px;
}

.owl-carousel .owl-item img {
    object-position: center;
    object-fit: cover;
}

in customizer -> additional CSS

yes here it is

Hi Peter,

i investigated a bit the demo and they have these styles you can add in your customizer -> additional CSS:

.owl-carousel .item-video {
    height: 300px;
}

Hi Peter

you can try 

.owl-carousel .owl-dots {
    top: 40px;
}

in customizer -> additional CSS

plz refer to Owl Carousel documentation for slider's settings and attributes - it's the best source of information.