html,body{
    height: 100%;
}

#cover{
    background: #222 url('background-photo.jpg') center center no-repeat;
    color: white;
    height: 100%;
    display: flex;
    text-align: center;
    align-items: center;
    -webkit-background-size: cover;
   -moz-background-size: cover;
   -o-background-size: cover;
   background-size: cover;
   height: 100%;
   width: 100% ;
}
#cover-caption{
    width: 100%;
}
@media only screen and (max-width: 767px) {
  #cover {
    /* The file size of this background image is 93% smaller
     * to improve page load speed on mobile internet connections */
    background-image: url(background-photo-mobile-devices.jpg);
  }
}
.mi-imagen-abajo-derecha{
    position:absolute;
    bottom:5px;
    right:10px;
    height: 70px;
    width: 70px;
}
.mi-imagen-abajo-izq{
    position:absolute;
    bottom:5px;
    right:110px;
    height: 70px;
    width: 70px;
}