[Theme: Attitude] Slider Image not Wide Enough

I’m using the Attitude Theme set to wide layout, but my images do not expand to the full screen. I have 3 images, all different sizes (1456×508, 1500 x 1163, and 1400 x 540) Here is my website https://www.luxeaffinitygroup.com. I’ve looked through other threads and have adjusted the image size and tried to adjust the function.php:

add_image_size( ‘slider-wide’, 1400, 460, true );

Nothing seems to work. Any other ideas? (I’m not technical at all, so it could be something obvious.)