Reply To: different slider settings for different widget areas

You should be able to add a background image by using the image uploader in your WP admin under “Customize“. If you want to add it directly to your CSS, you can look around line 1146 for this –

.slider-wide {	
    clear: both;
    width: 100%;
}

Then add the link to your background image like this –

.slider-wide {
    background-image: url(images/your_image_goes_here.jpg);	
    clear: both;
    width: 100%;
}