[Theme Horse Support Team]

Hi blazevic.is,
add_image_size( 'slider-wide', 1440, 500, true ); // used on Featured Slider on Homepage Header for wide layout
Just replace the above code with
add_image_size( 'slider-wide', 1960, 550, true ); // used on Featured Slider on Homepage Header for wide layout

Once before using download the regenerate thumbnails plugin and regenerate the thumbnails. Hope that may help you.

Thank you!