featured image size, single blog post

Hey team,

I have tried various support solutions I found in the threads but was unable to get the single blog featured image size to stop cropping the top.

I am using 600×600 images, But I want them content width 100% by full height. Basically a square. the theme cuts off some of the height by default. Tried adding this to the style sheet:
.big-preview img {
height: auto !important;
width: 100% !important;
}
also added this to the functions file:
$avia_config[‘imgSize’][‘entry_without_sidebar’]= array(‘width’=>1210, ‘height’=>1210, ‘crop’ => false );
did a regen images.
Is there something I missed?

Thanks for your help.

Steve