html, body {
  width: 100%;
  height: 100%;
}

.bg-img {
  position: relative;
  width: 100%;
  height: 100%;
  /*background: url("http://unsplash.it/1200x800") center center no-repeat;*/
  background-size: cover;
}
.bg-img:before {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  background-image: linear-gradient(to bottom right, #002f4b, #dc4225);
  opacity: .6;
}