.imgfondo {
  position: absolute;
  right: 0;
  width: 100%; 
  height: 100%;}

.imgfondo:after {
  content: "";
  position: absolute;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,.5);}

.i1 {background: url('../../images/portadas/p1.jpg');}
.i2 {background: url('../../images/portadas/p2.jpg'); background-position: 0 -50px;}
.i3 {background: url('../../images/portadas/p3.jpg');}
.i1, .i2, .i3 {background-size: cover;}