This is an example of the crossfade() function for blending background images.

50%

.hero { background-image: cross-fade ( 50 % url(https://cdn-images-1.medium.com/max/1600/1*o_vIFnBwhQIXh4qrzEYz7A.jpeg), url(https://www.desktopbackground.org/download/1600x900/2011/05/01/196572_audrey-hepburn-wallpapers-high-resolution-and-quality-download_2560x1920_h.jpg)); }