My homepage slider images are stretched, why?

Arc has a unique 50% – 50% page layout. There are only images on the left half.

There are some scripts in the theme which adjust background image (featured images and slider images) position,size etc. according to the user’s screen size. So there isn’t any specific image size for the left side of the pages. I suggest you to use high resolution and vertical images;

Bad Choice (400×300 px)

12

Good Choice (768×1154 px)

5