.substep {
      -webkit-transition: opacity 1s;
      -moz-transition:    opacity 1s;
      -ms-transition:     opacity 1s;
      -o-transition:      opacity 1s;
      transition:         opacity 1s;
    }
        
        
body {
  -webkit-transition: background 0;
  -moz-transition:    background 0;
  -ms-transition:     background 0;
  -o-transition:      background 0;
  transition:         background 0;
}

.substep {
  opacity: 0;
}

/* override for animated substeps */
.substep.anim {
  opacity: 1;
}

.substep.active {
  opacity: 1;
}


svg .substep.previous {
  opacity: 1; 
}

.substep.previous {
  opacity: 0.75;
}