$header-img: '~src/assets/images/home-background.jpg';
//add relative path variable
 background-image: linear-gradient(to right bottom , rgba(204, 137, 100, 0.8), rgba(40, 180, 133, 0.8)),url("#{$header-img}");
//or add relative path
/background-image: linear-gradient(to right bottom , rgba(204, 137, 100, 0.8), rgba(40, 180, 133, 0.8)), url('~src/assets/images/home-background.jpg');